Matching method and calibration device for single-rotation ellipsometer and double-rotation ellipsometer

Abstract

The application provides a matching method and a calibration device for a single-rotation ellipsometer and a double-rotation ellipsometer, comprising: obtaining a measured Mueller spectrum of a sample to be measured based on a double-rotation ellipsometer; obtaining a measured NCS spectrum of the sample to be measured based on a single-rotation ellipsometer; obtaining a converted NCS spectrum based on the measured Mueller spectrum and a detection angle of a detector of the double-rotation ellipsometer; calculating a difference between the converted NCS spectrum and the measured NCS spectrum; comparing the difference with a preset threshold value, and adjusting system parameters of at least one ellipsometer based on a comparison result until the difference between the converted NCS spectrum and the measured NCS spectrum is not greater than the preset threshold value. The application directly iterates the system parameters of the ellipsometers based on the measured Mueller spectrum and the measured NCS spectrum, does not need to obtain a to-be-measured parameter of the sample to be measured, can quickly match the two ellipsometers, completes calibration, and makes the measurement results of the two ellipsometers match / consistent.

Description

Technical Field

[0001] This invention relates to the field of semiconductor measurement, and more specifically, to a matching method and calibration device for a single-rotation elliptic measuring device and a dual-rotation elliptic measuring device. Background Technology

[0002] In the field of semiconductor metrology, optical measurement equipment plays a crucial role. Single-rotation ellipsometric measurement equipment and dual-rotation ellipsometric measurement equipment are two common types. Single-rotation ellipsometric measurement equipment includes single-rotation polarizer ellipsometric measurement equipment, single-rotation analyzer ellipsometric measurement equipment, and single-rotation compensator ellipsometric measurement equipment. In single-rotation compensator ellipsometric measurement, the rotary compensator can be mounted at the incident end (see...). Figure 1 It can also be installed at the exit end (see...). Figure 2 The structure of the dual-rotation elliptic measuring device is as follows: Figure 3 As shown.

[0003] For the same sample to be tested, under certain application scenarios, a single-rotation ellipsometer and a dual-rotation ellipsometer will be used to measure it. It is required that the difference between the measured parameters of the same sample obtained by the two devices (referring to the single-rotation ellipsometer and the dual-rotation ellipsometer) is not greater than a preset threshold, that is, the measurement results of the two devices are required to match.

[0004] The acquisition of analyte parameters from a sample using an optical ellipsometer typically involves: optical modeling of the sample; obtaining the measured Mueller spectrum based on the parameters of a dual-rotation ellipsometer system and the acquired measured spectrum; or obtaining the measured NCS spectrum based on the parameters of a single-rotation ellipsometer system and the acquired measured spectrum. Then, regression or library matching algorithms are used to match the measured Mueller spectrum with the theoretical Mueller spectrum, or the measured NCS spectrum with the theoretical NCS spectrum, to obtain the analyte parameters. To ensure matching between the measurement results of the two devices, existing techniques involve setting initial values ​​for the system parameters of both devices, then iteratively acquiring the measured Mueller and NCS spectra based on their current values. The analyte parameters are then obtained using the aforementioned method. The difference between the analyte parameters acquired by the two devices is then checked against a preset threshold. The iteration continues until the difference is no greater than the preset threshold, at which point the iteration ends, yielding the final values ​​of the system parameters for both devices. This calibrates the two devices, ensuring that their measurement results match or remain consistent. The above methods are very time-consuming and cannot calibrate the two devices in real time. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing a matching method and calibration device for a single-rotation elliptic measuring device and a double-rotation elliptic measuring device.

[0006] According to a first aspect of the present invention, a matching method for a single-rotation ellipsometric measuring device and a dual-rotation ellipsometric measuring device is provided, comprising:

[0007] Step 1: Obtain the measured Mueller spectrum of the sample under test using a dual-rotation ellipsometer.

[0008] Step 2: Obtain the measured NCS spectrum of the sample under test using a single-rotation ellipsometry.

[0009] Step 3: Based on the measured Mueller spectrum and the polarization angle of the analyzer of the dual rotating ellipsometer, obtain the converted NCS spectrum;

[0010] Step 4: Calculate the difference between the converted NCS spectrum and the measured NCS spectrum;

[0011] Step 5: Compare the difference with a preset threshold. If the difference is not greater than the preset threshold, the single-rotation elliptic measurement device and the double-rotation elliptic measurement device are matched.

[0012] If the difference is greater than a preset threshold, adjust the system parameters of the dual-rotation ellipsometer and / or the single-rotation ellipsometer until the difference between the converted NCS spectrum and the measured NCS spectrum is not greater than the preset threshold, so that the single-rotation ellipsometer and the dual-rotation ellipsometer are matched.

[0013] Based on the above technical solution, the present invention can also be improved as follows.

[0014] Optionally, step 2, based on the measured Mueller spectrum and the analyzer angle of the dual rotating ellipsometer, obtains the converted NCS spectrum, including:

[0015] Obtain the relationship between the Stokes vector and the Mueller matrix and the detection angle of the analyzer of the dual-rotation elliptic measuring device, denoted as the first relational expression;

[0016] The relationship between the NCS elements of the sample to be tested and the Stokes vector of the sample to be tested is obtained and denoted as the second relationship.

[0017] Based on the first and second relations, the relationship between the NCS elements of the sample to be tested and the Mueller matrix and the detection angle of the analyzer of the dual-rotation ellipsometric measuring device is obtained, and is denoted as the third relation.

[0018] Based on the third relation, the converted NCS spectrum is obtained by traversing each wavelength of the measured Mueller spectrum.

[0019] Optionally, obtaining the first relation includes:

[0020] The relationship between the Stokes vector of the sample to be tested and the Jones element of the sample to be tested and the detection angle of the analyzer of the dual-rotation elliptic measuring device is obtained and denoted as the fourth relationship.

[0021] The relationship between the Mueller matrix and the Jones matrix of the sample to be tested is obtained and denoted as the fifth relationship.

[0022] The first relation is obtained based on the fourth relation and the fifth relation.

[0023] Optionally, obtaining the fourth relation includes:

[0024] The relationship between the reflectance coefficient of the sample under test and the Jones matrix of the sample under test and the polarization angle of the analyzer of the dual-rotation ellipsometer is obtained and denoted as the sixth relationship.

[0025] The relationship between the Stokes vector of the sample to be tested and the reflectance coefficient of the sample to be tested is obtained and is denoted as the seventh relationship.

[0026] Based on the sixth relation and the seventh relation, the fourth relation is obtained.

[0027] Optionally, obtaining the sixth relation includes:

[0028] When the incident light is p-ray and the reflected light is p-ray, the reflectance coefficient of the sample is r. pp , get r pp The relationship between the Jones matrix of the sample to be tested and the detection angle of the analyzer in the dual-rotation elliptic measuring device is: r pp =J 11 +J 21 tanA;

[0029] When the incident light is s-ray and the reflected light is s-ray, the reflectance coefficient of the sample to be tested is r. ss , get r ss The relationship between the Jones matrix of the sample to be tested and the detection angle of the analyzer in the dual-rotation elliptic measuring device is: r ss =J 22 +J 12 tanA, where J 11 J 12 J 21 J 22 Let be the Jones element in the Jones matrix, and A be the detection angle of the analyzer in the dual-rotation elliptic measuring device.

[0030] Optionally, step 5, adjusting the system parameters of the dual-rotation ellipsometric measurement device and / or the single-rotation ellipsometric measurement device until the difference between the converted NCS spectrum and the measured NCS spectrum is no greater than a preset threshold, specifically includes:

[0031] Adjust the system parameters of the single-rotation elliptic measurement device using an iterative method, and repeat steps 2 and 4-5 until the difference is no greater than a preset threshold; or,

[0032] Adjust the system parameters of the dual-rotation ellipticity measurement device using an iterative method, and repeat steps 1 and 3-5 until the difference is no greater than a preset threshold; or,

[0033] The system parameters of the single-rotation elliptic measuring device and the dual-rotation elliptic measuring device are adjusted separately using the iterative method, and steps 1-5 are repeated until the difference is no greater than a preset threshold.

[0034] Optionally, the iterative method is at least one of gradient descent, Newton's method, and quasi-Newton's method.

[0035] Optionally, the difference is at least one of mean absolute error and mean square error.

[0036] Optionally, step 1 specifically includes: acquiring the first measurement spectrum of the sample to be tested based on a dual-rotation ellipsometer; and obtaining the measured Mueller spectrum based on the system parameters of the dual-rotation ellipsometer and the first measurement spectrum;

[0037] Step 2 specifically includes: acquiring the second measurement spectrum of the sample to be tested based on a single-rotation ellipsometric measurement device; and obtaining the measured NCS spectrum based on the system parameters of the single-rotation ellipsometric measurement device and the second measurement spectrum.

[0038] According to a second aspect of the present invention, a calibration apparatus for a single-rotation ellipsometric measurement device and a dual-rotation ellipsometric measurement device is provided. The calibration apparatus includes: a memory, a processor, and a calibration program stored in the memory and executable on the processor. The calibration program is configured to implement the matching method for the single-rotation ellipsometric measurement device and the dual-rotation ellipsometric measurement device described in the first aspect.

[0039] This invention provides a matching method and calibration device for a single-rotation ellipsometric measurement device and a dual-rotation ellipsometric measurement device. It directly iterates the system parameters of the two ellipsometric measurement devices based on the measurement of Mueller spectrum and the measurement of NCS spectrum. It can achieve rapid matching of the single-rotation ellipsometric measurement device and the dual-rotation ellipsometric measurement device without obtaining the measurement parameters of the sample to be measured. It has high calibration efficiency and makes the measurement results of the two ellipsometric measurement devices match / maintain consistency. Attached Figure Description

[0040] Figure 1 A schematic diagram of a single-rotation elliptic measurement device with a rotation compensator installed at the incident end;

[0041] Figure 2A schematic diagram of a single rotating elliptic measurement device with a rotating compensator installed at the output end;

[0042] Figure 3 This is a schematic diagram of the structure of a dual-rotation elliptic deflection measurement device.

[0043] Figure 4 A flowchart of a matching method for a single-rotation elliptic measuring device and a dual-rotation elliptic measuring device provided by the present invention;

[0044] Figure 5 This is a schematic diagram showing the residuals between the converted NCS spectrum and the measured NCS spectrum before iteration;

[0045] Figure 6 This is a schematic diagram of the residual between the transformed NCS spectrum and the measured NCS spectrum after iterative convergence. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined with each other to form feasible technical solutions. Such combinations are not constrained by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0047] Figure 4 A flowchart illustrating a matching method for a single-rotation elliptic measuring device and a dual-rotation elliptic measuring device provided by the present invention is shown below. Figure 4 As shown, the method includes:

[0048] Step 1: Obtain the measured Mueller spectrum of the sample to be tested using a dual-rotation ellipsometer.

[0049] Step 2: Obtain the measured NCS spectrum of the sample under test using a single-rotation ellipsometry.

[0050] Understandably, firstly, the initial values ​​of the system parameters of the single-rotation ellipsometric measurement device and the double-rotation ellipsometric measurement device are obtained respectively. For example, the system parameters include the initial optical axis azimuth angle of the analyzer, polarizer, and compensator. The optical axis azimuth angle is the angle between the optical axis and the incident plane.

[0051] Then, the first measurement spectrum of the sample is obtained using a dual-rotation ellipsometer. Based on the system parameters of the dual-rotation ellipsometer and the first measurement spectrum of the sample, the measurement Mueller spectrum is obtained. Similarly, using a single-rotation ellipsometer, for the same sample, the second measurement spectrum is obtained. Based on the system parameters of the single-rotation ellipsometer and the second measurement spectrum of the sample, the measurement NCS spectrum is obtained. Thus, the measurement NCS spectrum of the sample using a single-rotation ellipsometer and the measurement Mueller spectrum of the sample using a dual-rotation ellipsometer are obtained respectively.

[0052] Step 3: Based on the measured Mueller spectrum and the analyzer angle of the dual rotating ellipsometer, the converted NCS spectrum is obtained.

[0053] In this embodiment of the invention, the measured Mueller spectrum acquired by the dual-rotation ellipsometer is converted into an NSC spectrum. Specifically, based on the measured Mueller spectrum and the analyzer angle of the dual-rotation ellipsometer, the measured Mueller spectrum is converted into a measured NCS spectrum, hereinafter referred to as the converted NCS spectrum.

[0054] As an example, step 3, based on the measured Mueller spectrum and the polarization angle of the analyzer of the dual rotating ellipsometer, obtains the converted NCS spectrum, including:

[0055] Step S31: Obtain the relationship between the Stokes vector and the Mueller matrix and the analyzer angle of the dual-rotation elliptic measuring device, denoted as the first relational expression.

[0056] Obtaining the first relation includes:

[0057] Step S311: Obtain the relationship between the Stokes vector of the sample to be tested and the Jones element of the sample to be tested and the analyzer angle of the dual-rotation elliptic measuring device, denoted as the fourth relationship.

[0058] Specifically, obtaining the fourth relation includes:

[0059] a. Obtain the relationship between the reflection coefficient of the sample under test and the Jones matrix of the sample under test and the detection angle of the analyzer of the dual rotating ellipsometer, denoted as the sixth relationship.

[0060] When both the incident and reflected light are p-rays, the reflectance coefficient of the sample is r. pp , get r pp The relationship between the Jones matrix of the sample under test and the analyzer angle of the dual-rotation elliptic measuring device: r pp =J 11 +J 21 tanA.

[0061] When the incident light is s-ray and the reflected light is s-ray, the reflectance coefficient of the sample to be tested is r. ss , get r ss The relationship between the Jones matrix of the sample under test and the analyzer angle of the dual-rotation elliptic measuring device: r ss =J 22 +J 12 tanA, where J 11 J 12 J 21 J 22 is the Jones element in the Jones matrix, and A is the detection angle of the analyzer of the dual-rotation elliptic measuring device.

[0062] b. Obtain the relationship between the Stokes vector of the sample to be tested and the reflection coefficient of the sample to be tested, denoted as the seventh relationship.

[0063] The relationship between the Stokes vector of the sample and the reflectance coefficient of the sample is as follows:

[0064]

[0065] in, The reflection coefficient r pp conjugate, The reflection coefficient r ss The conjugate of , i is the imaginary unit, and S0, S1, S2, S3 are Stokes elements.

[0066] c. Based on the sixth and seventh relations, obtain the fourth relation of the Stokes vector of the sample to be tested with respect to the Jones element of the sample to be tested and the detection angle of the analyzer of the dual-rotation ellipsometric measuring device.

[0067] Understandably, substituting the sixth relation into the seventh relation yields the relationship between the Stokes vector of the sample under test and the Jones matrix of the sample under test and the detection angle A of the analyzer of the dual-rotation elliptic measuring device, denoted as the fourth relation, and expressed as follows:

[0068]

[0069]

[0070]

[0071]

[0072] in, Jones element J 11 J 12 J 21 J 22 . conjugate.

[0073] Step S312: Obtain the relationship between the Mueller matrix and the Jones matrix of the sample to be tested, denoted as the fifth relationship.

[0074] Understandably, the relationship between the Mueller matrix and the Jones matrix of the sample to be tested is as follows:

[0075]

[0076] Where M is the Mueller matrix and J is the Jones matrix.

[0077] Step S313: Based on the fourth and fifth relational expressions, obtain the first relational expression between the Stokes vector of the sample to be tested and the Mueller matrix of the sample to be tested and the detection angle of the analyzer of the dual rotating elliptic measuring device.

[0078] Understandably, substituting the fifth relationship between the Mueller matrix and the Jones matrix of the sample under test into the fourth relationship yields the relationship between the Stokes vector of the sample under test and the Mueller matrix of the sample under test and the detection angle A of the analyzer of the dual-rotation elliptic measuring device, denoted as the first relationship, and expressed as follows:

[0079] S0 = M 11 +M 22 +(M 31 +M 32 )tanA+(M 31 -M 32 )cotA+0.5*(M 21 -M 12 +M 11 -M 22 )cot 2 A+0.5*(M 11 -M 22 -M 21 +M 12 )tan 2 A

[0080] S1 = M 12 +M 21 +tanA(M 32 +M 31 )-cotA(M 31 -M 32 )-0.5*(M 21 -M 12 +M 11 -M 22 )cot 2 A+0.5*(M 11 -M 22 -M 21 +M 12 )tan2 A

[0081] S2 = 2M 33 +cotA(M 13 +M 23 )+tanA(M 13 -M 23 )

[0082] S3=i[-2iM 34 -i(M 14 +M 24 )cotA+i(M 24 -M 14 )tanA]

[0083] Among them, M 11 To M 34 These are the Mueller elements of the Mueller matrix M.

[0084] Step S32: Obtain the relationship between the NCS elements of the sample to be tested and the Stokes vector of the sample to be tested, denoted as the second relation.

[0085] The second relationship between the NCS elements and the Stokes vector of the sample to be tested is as follows:

[0086]

[0087] Step S33: Based on the first relation and the second relation, obtain the relationship between the NCS elements of the sample to be tested and the Mueller matrix and the analyzer angle of the dual-rotation ellipsometric measuring device, denoted as the third relation.

[0088] Substituting the first relation into the second relation, we obtain the relation between the NCS elements and the Mueller matrix M and the polarization angle A of the analyzer of the dual-rotation elliptic measuring device, denoted as the third relation, which is expressed as follows:

[0089]

[0090]

[0091]

[0092] Step S34: Based on the third relation, traverse each wavelength of the measured Mueller spectrum to obtain the converted NCS spectrum.

[0093] Understandably, based on the measured Mueller spectrum of the sample to be tested obtained by the dual-rotation ellipsometer and the analyzer's polarization angle, the measured Mueller spectrum is converted into the corresponding NCS spectrum based on the third relation, which is called the converted NCS spectrum.

[0094] The above method can obtain the converted NCS spectrum based on the measurement of the Mueller spectrum using a dual-rotation ellipsometer. For the same sample, the converted NCS spectrum and the measured NCS spectrum should be consistent. Therefore, this case uses the difference between the converted NCS spectrum and the measured NCS spectrum to adjust the system parameters of the two ellipsometers, eliminating the need for calculation of the measured parameters and thus greatly improving calibration efficiency.

[0095] Step 4: Calculate the difference between the converted NCS spectrum and the measured NCS spectrum.

[0096] The difference can be at least one of mean absolute error and mean square error.

[0097] Step 5: Compare the difference with a preset threshold. If the difference is not greater than the preset threshold, the single-rotation elliptic measurement device and the double-rotation elliptic measurement device are matched.

[0098] If the difference is greater than a preset threshold, adjust the system parameters of the dual-rotation ellipsometer and / or the single-rotation ellipsometer until the difference between the converted NCS spectrum and the measured NCS spectrum is not greater than the preset threshold, so that the single-rotation ellipsometer and the dual-rotation ellipsometer are matched.

[0099] Understandably, after converting the measured Mueller spectrum of the dual-rotation ellipsometer into an NCS spectrum, the converted NCS spectrum of the dual-rotation ellipsometer is compared with the measured NCS spectrum of the sample obtained by the single-rotation ellipsometer. The difference between the two is calculated. If the difference is not greater than a preset threshold, it indicates that the single-rotation ellipsometer and the dual-rotation ellipsometer are matched and no calibration is required.

[0100] If the difference between the two is greater than a preset threshold, the system parameters of the single-rotation ellipsometer and / or the dual-rotation ellipsometer are continuously adjusted until the difference between the converted NCS spectrum of the dual-rotation ellipsometer and the measured NCS spectrum of the single-rotation ellipsometer is no greater than a preset threshold. The final system parameters of the single-rotation ellipsometer and the dual-rotation ellipsometer are then obtained. Based on the final system parameters of the single-rotation ellipsometer and the dual-rotation ellipsometer, the system parameters of the single-rotation ellipsometer and the dual-rotation ellipsometer are calibrated respectively, thus achieving the calibration of the system parameters of the two ellipsometers. Compared with the existing technology, this eliminates the process of obtaining the test parameters of the sample, greatly improving efficiency, enabling real-time calibration of the two ellipsometers, and completing the matching of the two ellipsometers.

[0101] In the process of continuously adjusting the system parameters of the single-rotation ellipsometric measurement device and / or the dual-rotation ellipsometric measurement device, an iterative method is used to adjust the system parameters of the measurement device. This iterative method can be at least one of gradient descent, Newton's method, or quasi-Newton's method. For example, when using gradient descent to adjust the system parameters of the measurement device, a learning rate of 0.1 is set, and the first derivative of the difference between the system parameters of the ellipsometric measurement device after this iteration and the measured NCS spectrum and the converted NCS spectrum is calculated. The system parameters of the ellipsometric measurement device after this iteration are then subtracted from the product of the learning rate and the first derivative, and this product is used as the system parameters of the ellipsometric measurement device in the next iteration.

[0102] As an example, step 5 specifically includes:

[0103] Adjust the system parameters of the single-rotation elliptic measurement device using an iterative method, and repeat steps 2 and 4-5 until the difference is no greater than a preset threshold; or,

[0104] Adjust the system parameters of the dual-rotation ellipticity measurement device using an iterative method, and repeat steps 1 and 3-5 until the difference is no greater than a preset threshold; or,

[0105] The system parameters of the single-rotation elliptic measuring device and the dual-rotation elliptic measuring device are adjusted separately using the iterative method, and steps 1-5 are repeated until the difference is no greater than a preset threshold.

[0106] Understandably, if the system parameters of the single- and dual-rotation ellipsometric measurement devices are standard, then this invention only needs to iteratively adjust the system parameters of the single-rotation ellipsometric measurement device. Steps 2 and 4-5 need to be repeatedly executed until the difference between the measured NCS spectrum acquired by the single-rotation ellipsometric measurement device and the converted NCS spectrum acquired by the dual-rotation ellipsometric measurement device is no greater than a preset threshold. Then, the final system parameters of the single-rotation ellipsometric measurement device are obtained, and the system parameters of the single-rotation ellipsometric measurement device are calibrated based on these final system parameters. Similarly, if the system parameters of the single-rotation ellipsometric measurement device are standard, then this invention only needs to iteratively adjust the system parameters of the dual-rotation ellipsometric measurement device. Steps 1 and 3-5 need to be repeatedly executed until the difference between the converted NCS spectrum acquired by the dual-rotation ellipsometric measurement device and the measured NCS spectrum acquired by the single-rotation ellipsometric measurement device is no greater than a preset threshold. Then, the final system parameters of the dual-rotation ellipsometric measurement device are obtained, and the system parameters of the dual-rotation ellipsometric measurement device are calibrated based on these final system parameters. If the system parameters of both the single-rotation ellipsometer and the dual-rotation ellipsometer are not standard, it is necessary to iteratively adjust the system parameters of both devices separately. This requires repeatedly executing steps 1-5 until the difference between the measured NCS spectrum obtained by the single-rotation ellipsometer and the converted NCS spectrum obtained by the dual-rotation ellipsometer is no greater than a preset threshold. Then, obtain the final system parameters of both devices and calibrate them.

[0107] Furthermore, the step numbers in the various embodiments of this application are for the convenience of describing the technical solutions of this application, and are not a specific limitation on the order of implementation of each step.

[0108] It should be noted that if the system parameters of one of the two ellipsometric measuring devices are standard, then only the system parameters of the other ellipsometric measuring device need to be calibrated. When iteratively adjusting the system parameters, only the system parameters of the other ellipsometric measuring device need to be iterated.

[0109] in, Figure 5 The horizontal axis represents wavelength in nanometers, and the vertical axis represents the residual between the converted NCS spectrum before iteration and the measured NCS spectrum. Figure 6 The horizontal axis represents wavelength in nanometers, and the vertical axis represents the residual between the converted NCS spectrum and the measured NCS spectrum after iterative convergence.

[0110] Before iteration, based on the third relationship mentioned above, the converted NCS spectrum of the dual-rotation ellipsometric measurement device is obtained. Then, the mean square error (MSE) of the converted NCS spectrum and the measured NCS spectrum of the single-rotation ellipsometric measurement device is calculated (the MSEs of the N, C, and S spectra are obtained separately, then summed and divided by 3; the MSE is the sum of squares of the residuals). The MSE is 0.0003, and the preset threshold is 1e-6. If the MSE is greater than the preset threshold, the system parameters of the single-rotation ellipsometric measurement device and / or the dual-rotation ellipsometric measurement device are iterated until the difference between the measured NCS spectrum and the converted NCS spectrum is no greater than the preset threshold. Figure 6 As shown in the diagram, the residuals of the converted NCS spectrum and the measured NCS spectrum after convergence are shown. The mean square error of the converted NCS spectrum and the measured NCS spectrum is 1.15e-07, which is less than the preset threshold 1e-6. Thus, the final values ​​of the system parameters of the two devices are obtained. The final values ​​of the system parameters are used for the calibration of the two ellipsometric measurement devices, which can match the single-rotation ellipsometric measurement device and the dual-rotation ellipsometric measurement device, achieving matching / consistency of the measurement results of the single-rotation ellipsometric measurement device and the dual-rotation ellipsometric measurement device for the same sample.

[0111] Therefore, this invention provides a method for iterating the system parameters of two ellipsometric measurement devices directly based on measuring the Mueller spectrum and measuring the NCS spectrum. It can achieve rapid matching of single-rotation ellipsometric measurement devices and dual-rotation ellipsometric measurement devices without obtaining the test parameters of the test sample, and the calibration efficiency is high.

[0112] In addition, the present invention provides a calibration device for a single-rotation ellipsometric measurement device and a dual-rotation ellipsometric measurement device. The calibration device includes a memory, a processor, and a calibration program stored in the memory and executable on the processor. The calibration program is configured to implement the matching method for the single-rotation ellipsometric measurement device and the dual-rotation ellipsometric measurement device in the above embodiments.

[0113] This invention provides a matching method and calibration device for a single-rotation ellipsometric measurement device and a dual-rotation ellipsometric measurement device. The method involves acquiring the measured Mueller spectrum of the sample under test using the dual-rotation ellipsometric measurement device and the measured NCS spectrum of the same sample using the single-rotation ellipsometric measurement device. The measured Mueller spectrum is converted to obtain a converted NCS spectrum. The difference between the converted NCS spectrum and the measured NCS spectrum is calculated. If the difference is greater than a preset threshold, the system parameters of the dual-rotation ellipsometric measurement device and / or the single-rotation ellipsometric measurement device are adjusted. This process is repeated iteratively until the difference between the converted NCS spectrum and the measured NCS spectrum is no greater than the preset threshold. The final system parameters of the dual-rotation ellipsometric measurement device and the single-rotation ellipsometric measurement device are then obtained. The system parameters of the two devices are iterated directly based on the measured Mueller spectrum and the measured NCS spectrum, without needing to acquire the parameters of the sample under test. This achieves matching of the measurement results of the two ellipsometric measurement devices. Compared with existing technologies, the iteration process is faster and allows for real-time calibration of the two ellipsometric measurement devices, achieving matching / consistency of the measurement results.

[0114] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0115] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0116] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A matching method for a single-rotation elliptic measuring device and a double-rotation elliptic measuring device, characterized in that, include: Step 1: Obtain the measured Mueller spectrum of the sample under test using a dual-rotation ellipsometer. Step 2: Obtain the measured NCS spectrum of the sample under test using a single-rotation ellipsometry. Step 3: Based on the measured Mueller spectrum and the polarization angle of the analyzer of the dual rotating ellipsometer, obtain the converted NCS spectrum; Step 4: Calculate the difference between the converted NCS spectrum and the measured NCS spectrum; Step 5: Compare the difference with a preset threshold. If the difference is not greater than the preset threshold, the single-rotation elliptic measurement device and the double-rotation elliptic measurement device are matched. If the difference is greater than a preset threshold, adjust the system parameters of the dual-rotation ellipsometer and / or the system parameters of the single-rotation ellipsometer until the difference between the converted NCS spectrum and the measured NCS spectrum is not greater than the preset threshold, so that the single-rotation ellipsometer and the dual-rotation ellipsometer are matched. Step 3, which involves obtaining the converted NCS spectrum based on the measured Mueller spectrum and the polarization angle of the analyzer in the dual-rotation ellipsometer, includes: Obtain the third relationship between the NCS elements and the Mueller matrix M for measuring the Mueller spectrum and the polarization angle A of the analyzer in the dual-rotation ellipsometer. This third relationship is expressed as: Among them, M11 to M34 are the Mueller elements of the Mueller matrix M; Based on the third relation, the converted NCS spectrum is obtained by traversing each wavelength of the measured Mueller spectrum.

2. The method according to claim 1, characterized in that, Step 3, based on the measured Mueller spectrum and the polarization angle of the analyzer in the dual-rotation ellipsometer, obtains the converted NCS spectrum, including: Obtain the relationship between the Stokes vector and the Mueller matrix and the detection angle of the analyzer of the dual-rotation elliptic measuring device, denoted as the first relational expression; The relationship between the NCS elements of the sample to be tested and the Stokes vector of the sample to be tested is obtained and denoted as the second relationship. Based on the first and second relations, the relationship between the NCS elements of the sample to be tested and the Mueller matrix and the analyzer angle of the dual-rotation ellipsometric measuring device is obtained, and is denoted as the third relation.

3. The method according to claim 2, characterized in that, Obtaining the first relation includes: The relationship between the Stokes vector of the sample to be tested and the Jones element of the sample to be tested and the detection angle of the analyzer of the dual-rotation elliptic measuring device is obtained and denoted as the fourth relationship. The relationship between the Mueller matrix and the Jones matrix of the sample to be tested is obtained and denoted as the fifth relationship. The first relation is obtained based on the fourth relation and the fifth relation.

4. The method according to claim 3, characterized in that, Obtaining the fourth relation includes: The relationship between the reflectance coefficient of the sample under test and the Jones matrix of the sample under test and the polarization angle of the analyzer of the dual-rotation ellipsometer is obtained and denoted as the sixth relationship. The relationship between the Stokes vector of the sample to be tested and the reflectance coefficient of the sample to be tested is obtained and is denoted as the seventh relationship. Based on the sixth relation and the seventh relation, the fourth relation is obtained.

5. The method according to claim 4, characterized in that, Obtaining the sixth relation includes: When the incident light is p-ray and the reflected light is p-ray, the reflectance coefficient of the sample is r. pp , get r pp The relationship between the Jones matrix of the sample to be tested and the detection angle of the analyzer in the dual-rotation elliptic measuring device is: r pp =J 11 +J 21 tanA; When the incident light is s-ray and the reflected light is s-ray, the reflectance coefficient of the sample to be tested is r. ss , get r ss The relationship between the Jones matrix of the sample to be tested and the detection angle of the analyzer in the dual-rotation elliptic measuring device is: r ss =J 22 +J 12 tanA, where J 11 J 12 J 21 J 22 Let be the Jones element in the Jones matrix, and A be the detection angle of the analyzer in the dual-rotation elliptic measuring device.

6. The method according to claim 1, characterized in that, Step 5, adjusting the system parameters of the dual-rotation ellipsometer and / or the single-rotation ellipsometer until the difference between the converted NCS spectrum and the measured NCS spectrum is no greater than a preset threshold, specifically includes: Adjust the system parameters of the single-rotation elliptic measurement device using an iterative method, and repeat steps 2 and 4-5 until the difference is no greater than a preset threshold; or, Adjust the system parameters of the dual-rotation ellipticity measurement device using an iterative method, and repeat steps 1 and 3-5 until the difference is no greater than a preset threshold; or, The system parameters of the single-rotation elliptic measuring device and the dual-rotation elliptic measuring device are adjusted using an iterative method, and steps 1-5 are repeated until the difference is no greater than a preset threshold.

7. The method according to claim 6, characterized in that, The iterative method is at least one of gradient descent, Newton's method, and quasi-Newton's method.

8. The method according to claim 1, characterized in that, The difference is at least one of mean absolute error and mean square error.

9. The method according to claim 1, characterized in that, Step 1 specifically includes: acquiring the first measurement spectrum of the sample to be tested based on a dual-rotation ellipsometer; and obtaining the measured Mueller spectrum based on the system parameters of the dual-rotation ellipsometer and the first measurement spectrum. Step 2 specifically includes: acquiring the second measurement spectrum of the sample to be tested based on a single-rotation ellipsometric measurement device; and obtaining the measured NCS spectrum based on the system parameters of the single-rotation ellipsometric measurement device and the second measurement spectrum.

10. A calibration device for a single-rotation elliptic measuring device and a double-rotation elliptic measuring device, characterized in that, The calibration apparatus includes: a memory, a processor, and a calibration program stored in the memory and executable on the processor, the calibration program being configured to implement the matching method as described in any one of claims 1 to 9.

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