Optical measurement system, optical measurement method, and storage medium

Abstract

An optical measurement system, an optical measurement method, and a storage medium. The optical measurement system comprises: a plurality of measurement equipments of the same type, which include a standard first equipment (11) and at least one non-standard second equipment (12); and a controller, wherein the controller is connected to each measurement equipment, and is configured to: by means of the first equipment (11) and the second equipment (12), respectively acquire first spectral information and second spectral information of the same standard sample, and on the basis of the first spectral information and the second spectral information, calculate a corresponding first film thickness parameter and a corresponding second film thickness parameter; on the basis of the first film thickness parameter from the first equipment (11), and an optical system parameter and / or sample model parameter for the second equipment (12), construct and solve an optimization equation for the second spectral information, so as to optimize the optical system parameter and / or sample model parameter for the second equipment (12); and by means of the first equipment (11) and the at least one second equipment (12) and on the basis of optical system parameters and / or sample model parameters corresponding thereto, test in parallel a plurality of samples to be tested.

Description

Optical measurement system, optical measurement method and storage medium Technical Field

[0001] The present invention relates to the field of optical measurement and detection, and in particular to an optical measurement system, an optical measurement method, and a computer-readable storage medium. Background Art

[0002] Semiconductor optical measurement equipment, as a crucial measurement tool, is widely used in the semiconductor processing field. Optical measurement equipment can obtain sample properties such as film thickness and critical dimensions based on the collected spectral information of the sample, combined with the sample model and system optical parameters. However, in actual measurement processes, slight deviations in hardware parameters between equipment units during production, slight differences in optical system parameters during debugging, and random errors in the equipment during the measurement process can lead to inconsistent measurement results from the same measurement model on the same type of measurement equipment.

[0003] In order to eliminate the differences in measurement results caused by the above-mentioned hardware parameter deviations, attempts have been made in the field to improve the processing accuracy of each hardware module of the measurement system so that the hardware parameters are consistent. However, this method not only greatly increases the manufacturing cost of the equipment, but also cannot completely eliminate hardware errors. In addition, a method for calibrating optical system parameters has been proposed in the field. By using standard samples to calibrate the parameters of the optical system between multiple machines, the parameters of the optical systems on different machines are corrected, thereby improving the matching accuracy of the measurement results between the machines. However, this method still cannot completely avoid the phenomenon of measurement result mismatch caused by external interference factors such as machine position offset, air humidity changes, and differences in ambient light distribution.

[0004] In order to overcome the above-mentioned defects of the prior art, there is an urgent need in the art for an improved optical measurement system for improving the matching accuracy of measurement results between multiple machines without changing the hardware system and optical system components.

[0005] Summary of the Invention

[0006] The following is a brief summary of one or more aspects to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceivable aspects and is neither intended to identify key or critical elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that will be provided later.

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides an optical measurement system, an optical measurement method and a computer-readable storage medium, which are used to fit the measurement results between different machines of the same model through the same measurement model without changing the hardware system and optical system components, and to correct the system parameters and model parameters based on the fitting results, thereby improving the matching accuracy of the measurement results between multiple machines.

[0008] Specifically, the optical measurement system provided according to the first aspect of the present invention includes a plurality of measurement machines of the same type and a controller. The plurality of measurement machines of the same type include a standard first machine and at least one non-standard second machine. The controller is connected to each of the measurement machines and is configured to: obtain the first spectral information and the second spectral information of the same standard sample via the first machine and the second machine, respectively, and calculate the corresponding first film thickness parameter and second film thickness parameter accordingly; construct and solve the optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine; and detect multiple samples to be tested in parallel via the first machine and at least one of the second machines, respectively, according to their corresponding optical system parameters and / or sample model parameters.

[0009] Furthermore, in some embodiments of the present invention, the standard sample includes a plurality of measurement units j. The step of constructing and solving an optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine includes: determining the first film thickness parameter T_Ref respectively. j and the second film thickness parameter T_Meas of the second machine i ij The thickness difference T_Diff in each of the measuring units ij According to each thickness difference T_Diff ij The absolute value of the second machine i and the first machine are used to select multiple target measurement units z with the largest detection deviation between them. im ; and according to the plurality of target measurement units z im The first film thickness parameter And the optical system parameters SysParam of the second machine i i and / or sample model parameters NK i , construct and solve the problem about the multiple target measurement units z im Second spectrum information The optimization equation is used to determine the optimized optical system parameters SysParam_Fit of the second machine i i and / or sample model parameters NK_Fit i .

[0010] Furthermore, in some embodiments of the present invention, the optimization equation is expressed as:

[0011] The steps of solving the optimization equation include: using the Levenberg-Marquardt optimization algorithm to fit the optical system parameters SysParam i and / or the sample model parameter NK i To determine and correct the second machine i and the first machine in the multiple target measurement units z im Optical system parameters for detecting deviations SysParam_Fit i and / or sample model parameters NK_Fit i .

[0012] Furthermore, in some embodiments of the present invention, the Levenberg-Marquardt optimization algorithm is used to fit the optical system parameters SysParam i and / or the sample model parameter NK i To determine and correct the second machine i and the first machine in the multiple target measurement units z im Optical system parameters for detecting deviations SysParam_Fit i and / or sample model parameters NK_Fit i The steps include: determining the corresponding theoretical spectrum according to the optical system parameter SysParam, the film thickness T and the sample model parameter NK:

[0013] Spec_Theory=f(SysParam, T, NK);

[0014] Construct an objective function by fitting the optical system parameters SysParam and the sample model parameters NK to make the measured spectrum Spec_Measure close to the theoretical spectrum Spec_Theory:

[0015] The first film thickness parameter The objective function is brought into play, and the Levenberg-Marquardt optimization algorithm is used to calculate the optimal solution SysParam_Fit of the optical system parameters and the optimal solution NK_Fit of the sample model parameters that minimize |f(SysParam, T, NK)-Spec_Measure|.

[0016] Furthermore, in some embodiments of the present invention, the optical system parameters include the incident light cone angle AOI and / or the numerical aperture NA of the detection light. The sample model parameters include the refractive index N and / or the absorption coefficient K of the sample material. The step of constructing and solving the optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine includes: obtaining a selection instruction for the optical system parameters and / or the sample model parameters; and constructing and solving the optimization equation for the second spectral information based on the selection instruction to optimize the optical system parameters and / or sample model parameters selected on the second machine.

[0017] Furthermore, in some embodiments of the present invention, the refractive index N and / or the absorption coefficient K is a function of the wavelength λ:

[0018] N=f1(λ),

[0019] K = f2(λ).

[0020] The step of constructing and solving an optimization equation about the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine includes: solving the optimization equation to optimize the first function f1(·) of the refractive index N and / or the second function f2(·) of the absorption coefficient K.

[0021] Furthermore, in some embodiments of the present invention, the step of detecting multiple samples to be tested in parallel via the first machine and at least one of the second machines according to their corresponding optical system parameters and / or sample model parameters includes: in response to completing the optimization of the optical system parameters and / or sample model parameters of the second machine, re-acquiring the third spectral information and fourth spectral information of multiple verification samples via the first machine and the second machine that completes the optimization, and calculating the corresponding third film thickness parameters and fourth film thickness parameters accordingly; calculating the correlation degree and / or root mean square error between the third film thickness parameters and the fourth film thickness parameters of the multiple verification samples; and in response to the correlation degree being greater than a preset first threshold, and / or the root mean square error being less than a preset second threshold, detecting multiple samples to be tested in parallel via the first machine and the second machine that completes the optimization according to their corresponding optical system parameters and / or sample model parameters.

[0022] Furthermore, in some embodiments of the present invention, the step of detecting a plurality of samples to be tested in parallel via the first machine and at least one of the second machines according to their corresponding optical system parameters and / or sample model parameters also includes: counting the time and / or quantity of the first machine and the second machine that completes the optimization detecting the samples to be tested in parallel; and re-optimizing the optical system parameters and / or sample model parameters of the second machine in response to the time reaching a preset time threshold and / or the quantity reaching a preset quantity threshold.

[0023] Furthermore, the optical measurement method provided in accordance with the second aspect of the present invention includes the following steps: obtaining first spectral information and second spectral information of the same standard sample via a standard first machine and at least one non-standard second machine, the first machine and the second machine being the same type of measurement machine; calculating a corresponding first film thickness parameter based on the first spectral information, and calculating a corresponding second film thickness parameter based on the second spectral information; constructing and solving an optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine; and concurrently testing a plurality of samples to be tested via the first machine and the at least one second machine, based on their corresponding optical system parameters and / or sample model parameters.

[0024] Furthermore, the computer-readable storage medium provided in accordance with the third aspect of the present invention stores computer instructions, which, when executed by a processor, implement the optical measurement method provided in accordance with the second aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or characteristics may have the same or similar reference numerals.

[0026] FIG1 shows a schematic diagram of the architecture of an optical measurement system according to some embodiments of the present invention.

[0027] FIG2 is a schematic flow chart showing an optical measurement method according to some embodiments of the present invention.

[0028] FIG3 shows a schematic diagram of a measurement unit for a standard sample according to some embodiments of the present invention.

[0029] FIG. 4 shows a line graph of film thickness parameters measured by a reference tool and various measurement tools before correction according to some embodiments of the present invention.

[0030] FIG. 5 shows a correlation diagram of film thickness parameters measured by a reference tool and a measurement tool #1 before correction, provided by some embodiments of the present invention.

[0031] FIG. 6 shows a correlation diagram of film thickness parameters measured by a reference tool and a measurement tool #2 before correction provided by some embodiments of the present invention.

[0032] FIG. 7 shows a comparison diagram of errors between film thickness parameters measured by a reference tool and various measurement tools before correction according to some embodiments of the present invention.

[0033] FIG. 8 shows a line graph of film thickness parameters measured by a reference tool and various corrected measurement tools according to some embodiments of the present invention.

[0034] FIG. 9 shows a correlation diagram of film thickness parameters measured by a reference tool and a modified measurement tool #1 according to some embodiments of the present invention.

[0035] FIG. 10 shows a correlation diagram of film thickness parameters measured by a reference tool and a modified measurement tool #2 according to some embodiments of the present invention.

[0036] FIG. 11 shows a comparison diagram of errors of film thickness parameters measured by a reference tool and various corrected measuring tools according to some embodiments of the present invention. DETAILED DESCRIPTION

[0037] The following specific embodiments illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0039] Furthermore, the terms "upper," "lower," "left," "right," "top," "bottom," "horizontal," and "vertical" used in the following description should be understood to refer to the orientations depicted in that section and the accompanying drawings. These relative terms are used solely for convenience of description and do not necessarily imply that the devices described herein must be manufactured or operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0040] It will be understood that although the terms "first," "second," "third," etc. may be used herein to describe various components, regions, layers, and / or portions, these components, regions, layers, and / or portions should not be limited by these terms, and these terms are merely used to distinguish different components, regions, layers, and / or portions. Thus, a first component, region, layer, and / or portion discussed below may be referred to as a second component, region, layer, and / or portion without departing from some embodiments of the present invention.

[0041] As mentioned above, in the actual measurement process of semiconductor devices, there may be slight deviations in the hardware parameters of the equipment during the production process, or there may be slight differences in the optical system parameters during the debugging process. In addition, the equipment may also produce random errors during the measurement process. As a result, the measurement results of the same measurement model on the same type of measurement equipment cannot be completely matched.

[0042] In order to eliminate the differences in measurement results caused by the above-mentioned hardware parameter deviations, attempts have been made in the field to improve the processing accuracy of each hardware module of the measurement system so that the hardware parameters are consistent. However, this method not only greatly increases the manufacturing cost of the equipment, but also cannot completely eliminate hardware errors. In addition, a method for calibrating optical system parameters has been proposed in the field. By using standard samples to calibrate the parameters of the optical system between multiple machines, the parameters of the optical systems on different machines are corrected, thereby improving the matching accuracy of the measurement results between the machines. However, this method still cannot completely avoid the phenomenon of measurement result mismatch caused by external interference factors such as machine position offset, air humidity changes, and differences in ambient light distribution.

[0043] In order to overcome the above-mentioned defects of the prior art, the present invention provides an optical measurement system, an optical measurement method and a computer-readable storage medium, which are used to fit the measurement results between different machines of the same model through the same measurement model without changing the hardware system and optical system components, and to correct the system parameters and model parameters based on the fitting results, thereby improving the matching accuracy of the measurement results between multiple machines.

[0044] In some non-limiting embodiments, the optical measurement method provided in the second aspect of the present invention can be implemented based on the optical measurement system provided in the first aspect of the present invention.

[0045] Please refer to FIG. 1 for details. FIG. 1 shows a schematic structural diagram of an optical measurement system according to some embodiments of the present invention.

[0046] In the embodiment shown in FIG1 , the optical measurement system provided by the first aspect of the present invention includes multiple measurement machines of the same type, a memory, and a controller. The multiple measurement machines of the same type include a standard first machine 11 and at least one non-standard second machine 12. The memory includes, but is not limited to, the computer-readable storage medium provided by the third aspect of the present invention, which stores computer instructions. The controller is connected to each measurement machine and the memory and is configured to control each measurement machine to execute the computer instructions stored in the memory to implement the optical measurement method provided by the second aspect of the present invention.

[0047] The following describes the operating principles of the aforementioned optical measurement system, using examples of methods for aligning irregular samples. Those skilled in the art will appreciate that these measurement method examples are merely non-limiting implementations of the present invention, intended to clearly demonstrate the main concepts of the present invention and provide specific solutions for easy implementation by the public. They do not limit the full functionality or operation of the optical measurement system. Similarly, the optical measurement system is merely a non-limiting implementation of the present invention and does not restrict the execution of the various steps in these measurement methods, nor does it limit their execution order.

[0048] Please refer to Figures 1 to 3. Figure 2 shows a schematic flow chart of an optical measurement method according to a second aspect of the present invention. Figure 3 shows a schematic diagram of a measurement unit for a standard sample according to some embodiments of the present invention.

[0049] As shown in Figures 1 and 2, before performing optical measurement of semiconductor devices, the optical measurement system can first obtain the first spectral information and the second spectral information of the same standard sample through a standard first machine 11 and at least one non-standard second machine 12. Here, the first machine 11 and the second machine 12 are the same type of measurement machines. As shown in Figure 3, the standard sample includes a plurality of measurement units j. The measurement unit j can be divided according to the die of the semiconductor device. The optical measurement system can obtain the first spectral information Spec_Ref of the jth measurement unit of the same standard sample through the first machine 11 and the i-th second machine 12. j And the second spectrum information Spec_Meas ij .

[0050] Afterwards, the optical measurement system can use the ellipsometry measurement principle to obtain the first spectral information Spec_Ref. j Calculate the corresponding first film thickness parameter T_Ref j , and according to the second spectrum information Spec_Meas ij Calculate the corresponding second film thickness parameter T_Meas ij .

[0051] Next, the optical measurement system can preferably receive a user's selection instruction for the optical system parameter SysParam and / or the sample model parameter NK. Based on the selection instruction, it constructs and solves an optimization equation for the second spectral information using the optical system parameter SysParam and / or the sample model parameter NK as parameters, thereby optimizing the selected optical system parameter and / or sample model parameter for each non-standard second machine 12. Here, the optical system parameter SysParam includes the incident light cone angle AOI and / or the numerical aperture NA of the detection light. The sample model parameter NK includes the refractive index N and / or absorption coefficient K of the sample material.

[0052] Furthermore, the refractive index N and / or the absorption coefficient K may be a function of the wavelength λ:

[0053] N=f1(λ),

[0054] K = f2(λ).

[0055] Therefore, when the above selection instruction involves the optimization requirement of the refractive index N and / or the absorption coefficient K, the optical measurement system can also correspondingly optimize the first function f1(·) of the refractive index N and / or the second function f2(·) of the absorption coefficient K to improve the matching accuracy of the measurement results between each non-standard second machine 12 and the standard first machine 11.

[0056] Specifically, the optical measurement system can first determine the first film thickness parameter T_Ref as follows: j and the second film thickness parameter T_Meas of the i-th second machine 12 ij Thickness difference T_Diff in each measuring unit j ij :

[0057] T_Diff ij =|T_Meas ij -T_Ref j |

[0058] Afterwards, the optical measurement system can measure the thickness difference T_Diff ij The absolute values ​​of the two are sorted from large to small, and the k target measurement units z with the largest detection deviation between the i-th second machine 12 and the first machine 11 are selected. im (m=1, 2, ..., k).

[0059] Then, the optical measurement system can measure the units z according to multiple targets. im The first film thickness parameter The optical system parameter SysParam of the i-th second machine 12 i and / or sample model parameters NK i , determine and correct the optical system parameter SysParam_Fit of the i-th second machine 12 i and / or sample model parameters NK_Fit i , and the multiple target measurement units z im Second spectrum information The optimization equation is expressed as:

[0060] Specifically, for each target measurement unit z im , the optical measurement system can measure the target unit zim The optical system parameters SysParam, film thickness T and sample model parameters NK are used to determine the corresponding theoretical spectrum:

[0061] Spec_Theory=f(SysParam,T,NK)

[0062] Afterwards, the optical measurement system can use the Levenberg-Marquardt optimization algorithm to continuously fit the optical system parameters SysParam and the sample model parameters NK to construct an objective function that makes the measured spectrum Spec_Measure close to the theoretical spectrum Spec_Theory:

[0063] Afterwards, the optical measurement system can measure the first film thickness parameter Substitute the objective function and use the Levenberg-Marquardt optimization algorithm to calculate the optimal solution SysParam_Fit of the optical system parameters and the optimal solution NK_Fit of the sample model parameters that minimize |f(SysParam, T, NK)-Spec_Measure|.

[0064] Those skilled in the art will understand that the abstract function f(·) used in the above optimization equation and theoretical spectrum is only a simplified description provided by the present invention, which is intended to clearly illustrate the main concept of the present invention, and is not intended to limit the scope of protection of the present invention.

[0065] Specifically, the abstract function f(·) can represent the process of calculating the theoretical spectrum Spec_Theory based on the optical system parameters SysParam such as the incident angle AOI, the numerical aperture NA, the polarization angle P, the analyzer angle A, the film thickness T, and the sample model parameter NK. Here, the present invention can use the Fourier coefficient (Alpha Meas , Beta Meas ) to represent the actual spectrum collected by the spectrometer And the Fourier coefficient (Alpha Theory， Beta Theory ) to characterize the theoretical spectrum Spec_Theory.

[0066] The following briefly describes how to calculate the theoretical Fourier coefficient (Alpha Theory， Beta Theory ) process. Taking the rotating analyzer ellipsometer (RAE) and a single-layer film as an example, we first need to describe the incident light. Since light is an electromagnetic wave, it has two polarization directions, p-polarization and s-polarization. After the reflection of the sample to be measured, the R of the reflected light can be obtained. p 、Rs The calculation formula is as follows:

[0067] Among them, R p Refers to the component of the reflected light along the p-polarization direction, R s It refers to the component of the reflected light along the s-polarization direction, N0 and N1 are the material parameters of the sample to be tested, θ0 and θ1 are the incident angle and refraction angle respectively, and θ1 needs to be calculated based on the film thickness parameters and wavelength.

[0068] Furthermore, after obtaining the reflected light R p 、R s Then, the present invention can use the Stokes formula to convert R p and R s Convert to Fourier coefficients of spectrum:

[0069] Among them, Alpha and Beta are the Fourier coefficients of the theoretical spectrum, and A is the analyzer angle.

[0070] Afterwards, in the actual measurement process, the present invention can convert the collected spectrum into the measured Fourier coefficients (Alpha Meas , Beta Meas ), and the theoretical Fourier coefficients (Alpha Theory, Beta Theory ). Afterwards, the present invention can adjust the optical system parameter SysParam and the sample model parameter NK as described above to minimize the difference between the theoretically calculated Fourier coefficients and the actually measured Fourier coefficients.

[0071] As can be seen from the calculation process of the Fourier coefficients above, the calculation process of the Fourier coefficients is nonlinear, that is, the objective function is also a nonlinear objective function. Therefore, the present invention can select the Levenberg-Marquardt optimization algorithm suitable for solving nonlinear optimization problems to solve the above nonlinear objective function.

[0072] Specifically, in the process of solving the above nonlinear objective function using the Levenberg-Marquardt optimization algorithm, the present invention can first calculate the Jacobian matrix J corresponding to the optimization parameter x0, and then solve the following equation to calculate the step size Δx of each optimization parameter based on the damping factor:

[0073] (J T J+μI)Δx=-J T ·f

[0074] Where μ is the damping factor, I is the identity matrix, and f is the objective function value.

[0075] Afterwards, the present invention can add the calculated step length Δx to the initial value of the above-mentioned optimization parameter x0.

[0076] x′=x0+Δx

[0077] Then, according to the above Levenberg-Marquardt optimization algorithm, the optical system parameters SysParam and sample model parameters NK that need to be fitted are calculated.

[0078] In this way, the optical measurement system can detect multiple samples in parallel through the first machine 11 and at least one second machine 12 according to their corresponding optical system parameters SysParam and / or sample model parameters NK.

[0079] Specifically, in response to the completion of the optimization of the optical system parameters and / or sample model parameters of the second machine 12, the optical measurement system can re-acquire the third spectral information and the fourth spectral information of the plurality of calibration samples via the first machine 11 and the optimized second machine 12, and calculate the corresponding third film thickness parameter and the fourth film thickness parameter accordingly.

[0080] Afterwards, the optical measurement system can calculate the correlation degree R between the third film thickness parameter and the fourth film thickness parameter of the plurality of calibration samples. 2 And / or root mean square error RMSE. In response to the correlation degree R 2 If the value is greater than a preset first threshold and / or the root mean square error RMSE is less than a preset second threshold, it can be determined that the optimization of the second machine 12 is completed.

[0081] Thereafter, the optical measurement system can detect a plurality of samples to be tested in parallel via the first machine 11 and the optimized second machine 12 according to their corresponding optical system parameters and / or sample model parameters.

[0082] Furthermore, when testing multiple samples, the optical measurement system can count the time and / or number of samples tested in parallel by the first machine 11 and the optimized second machine 12. In response to the time reaching a preset time threshold and / or the number reaching a preset number threshold, the optical measurement system can re-optimize the optical system parameters and / or sample model parameters of the second machine 12 to prevent deviations in the parameters of the second machine 12 due to long-term use, thereby ensuring the matching accuracy of the first machine 11 and the second machine 12.

[0083] In order to verify the correction effect of the optical measurement method provided in the second aspect of the present invention, a reference example is further provided below for comparing film thickness parameters measured by a standard reference machine and the measurement machine before and after correction.

[0084] In this comparative example, the present invention employs a reference instrument and two measurement instruments within an optical measurement system to measure a sample. The film thickness parameters obtained by the reference instrument and the measurement instruments before and after correction are compared. The sample to be measured is a thin film using a harmonic oscillator material model. The two measurement instruments are designated Instrument #1 and Instrument #2.

[0085] Please refer to Figures 4 to 11. Figure 4 shows a line graph of film thickness parameters measured by a reference machine and each measuring machine before correction according to some embodiments of the present invention. Figure 5 shows a correlation graph of film thickness parameters measured by a reference machine and measuring machine #1 before correction according to some embodiments of the present invention. Figure 6 shows a correlation graph of film thickness parameters measured by a reference machine and measuring machine #2 before correction according to some embodiments of the present invention. Figure 7 shows a comparison graph of the errors between film thickness parameters measured by a reference machine and each measuring machine before correction according to some embodiments of the present invention. Figure 8 shows a line graph of film thickness parameters measured by a reference machine and each measuring machine after correction according to some embodiments of the present invention. Figure 9 shows a correlation graph of film thickness parameters measured by a reference machine and measuring machine #1 after correction according to some embodiments of the present invention. Figure 10 shows a correlation graph of film thickness parameters measured by a reference machine and measuring machine #2 after correction according to some embodiments of the present invention. Figure 11 shows a comparison graph of the errors between film thickness parameters measured by a reference machine and each measuring machine after correction according to some embodiments of the present invention.

[0086] As shown in Figures 4 to 7, there are obvious differences in the film thickness parameters measured by the reference machine and the measurement machines #1 and #2 before correction. The correlation between the film thickness parameters measured by the measurement machine #1 and the reference machine, R 2 =0.9188, RMSE = 0.7448. Correlation R between the film thickness parameters measured by measuring machine #2 and the reference machine 2 =0.9181, root mean square error RMSE = 1.8232.

[0087] As shown in Figures 8 to 11, the difference between the film thickness parameters measured by the reference machine and the corrected measurement machines #1 and #2 is significantly reduced. It can be calculated that the correlation degree R between the film thickness parameters measured by measurement machine #1 and the reference machine is 2 =0.9461, which is 2.97% higher than the correlation before correction. The root mean square error (RMSE) of the film thickness parameters measured by measuring machine #1 and the reference machine is 0.6930, which is 6.9% lower than the root mean square error before correction. The correlation R between the film thickness parameters measured by measuring machine #2 and the reference machine is2 =0.9443, a 2.85% improvement in correlation compared to the pre-correction level. The root mean square error (RMSE) of the film thickness parameters measured by measurement machine #2 and the reference machine is 1.1235, a 38.38% reduction compared to the pre-correction level.

[0088] It can be seen that the matching accuracy of the film thickness parameters measured by the two measuring machines #1 and #2 after the correction of the above-mentioned optical measurement method provided by the second aspect of the present invention and the film thickness parameters measured by the reference machine has been improved, especially the improvement on the measuring machine #2 is more significant.

[0089] In summary, the optical measurement system, optical measurement method, and computer-readable storage medium provided by the present invention can, without changing the hardware system and optical system components, fit the measurement results between different machines of the same model using the same measurement model, and correct the system parameters and model parameters based on the fitting results, thereby improving the matching accuracy of the measurement results between machines.

[0090] Although the above methods are illustrated and described as a series of acts for simplicity of explanation, it is to be understood and appreciated that these methods are not limited by the order of the acts, as some acts may occur in a different order and / or concurrently with other acts from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art according to one or more embodiments.

[0091] Those skilled in the art will appreciate that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips cited throughout the foregoing description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0092] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optical measurement system, characterized in that, Including: Multiple measurement machines of the same type, including a standard first machine and at least one non-standard second machine; And A controller, connected to each of the measurement stations, and configured to: obtain first spectral information and second spectral information of the same standard sample via the first station and the second station i respectively, and calculate first film thickness parameters T_Ref of multiple measurement units j in the standard sample accordingly j and second film thickness parameters T_Meas ij the thickness difference T_Diff between them ij ; according to each of the thickness differences T_Diff ij the absolute value of, screen multiple target measurement units z with the largest detection deviation between the second station i and the first station im ; according to the first film thickness parameters T_Ref of the multiple target measurement units z im and the optical system parameters SysParam of the second station i j and / or the sample model parameters NK i construct and solve the second spectral information about the multiple target measurement units z i im ​​ Optimization equation, where the optimization equation is expressed as Adopt an optimization algorithm to fit the optical system parameters SysParam i and / or the sample model parameters NK i , to determine the optical system parameters SysParam_Fit im for correcting the detection deviation between the second machine stage i and the first machine stage at the multiple target measurement units z i and / or the sample model parameters NK_Fit i ; And respectively detecting multiple samples to be measured in parallel via the first machine and at least one of the second machines i according to their corresponding optical system parameters and / or sample model parameters.

2. The optical measurement system according to claim 1, wherein The optimization algorithm includes the Levenberg-Marquardt algorithm.

3. The optical measurement system according to claim 2, wherein Adopt an optimization algorithm to fit the optical system parameters SysParam i and / or the sample model parameters NK i , to determine the optical system parameters SysParam_Fit im for correcting the detection deviation between the second machine stage i and the first machine stage at the multiple target measurement units z i and / or the sample model parameters NK_Fit i The steps are as follows: Determine the corresponding theoretical spectrum according to the optical system parameter SysParam, the film thickness T, and the sample model parameter NK: Spec_Theory = f(SysParam, T, NK); Construct an objective function that fits the optical system parameters SysParam and the sample model parameters NK to make the measured spectrum Spec_Measure close to the theoretical spectrum Spec_Theory: The first film thickness parameter Substitute into the objective function and calculate the optimal solution SysParam_Fit of the optical system parameter and the optimal solution NK_Fit of the sample model parameter that minimize |f(SysParam, T, NK) - Spec_Measure| through the Levenberg-Marquardt optimization algorithm.

4. The optical measurement system according to claim 1, wherein The optical system parameters include the incident light cone angle AOI and / or the numerical aperture NA of the detection light, and the sample model parameters include the refractive index N and / or the absorption coefficient K of the sample material. The steps of constructing and solving an optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine include: Obtain a selection instruction for the optical system parameters and / or the sample model parameters; and According to the selection instruction, construct and solve an optimization equation for the second spectral information to optimize the selected optical system parameters and / or sample model parameters on the second machine.

5. The optical measurement system according to claim 4, wherein The refractive index N and / or the absorption coefficient K are functions of the wavelength λ: N = f1(λ) K = f2(λ) The steps of constructing and solving an optimization equation for the second spectral information based on the first film thickness parameter of the first machine and the optical system parameters and / or sample model parameters of the second machine to optimize the optical system parameters and / or sample model parameters of the second machine include: Solve the optimization equation to optimize the first function f1(·) of the refractive index N and / or the second function f2(·) of the absorption coefficient K.

6. The optical measurement system according to claim 1, wherein The steps of respectively detecting multiple samples to be measured in parallel via the first machine and at least one of the second machines according to their corresponding optical system parameters and / or sample model parameters include: In response to completing the optimization of the optical system parameters and / or sample model parameters of the second machine, re-obtain the third spectral information and the fourth spectral information of multiple calibration samples via the first machine and the second machine that has completed the optimization, and calculate the corresponding third film thickness parameter and the fourth film thickness parameter based on this; Calculate the correlation degree and / or the root mean square error between the third film thickness parameter and the fourth film thickness parameter of the multiple calibration samples; and In response to the degree of correlation being greater than a preset first threshold, and / or the root mean square error being less than a preset second threshold, multiple samples to be measured are detected in parallel via the first machine tool and the second machine tool that has completed the optimization, respectively according to their corresponding optical system parameters and / or sample model parameters.

7. The optical measurement system according to claim 6, wherein The step of detecting multiple samples to be measured in parallel via the first machine tool and at least one of the second machine tools, respectively according to their corresponding optical system parameters and / or sample model parameters, further includes: statistical time and / or quantity of the first machine tool and the second machine tool that has completed the optimization detecting the samples to be measured in parallel; and in response to the time reaching a preset time threshold and / or the quantity reaching a preset quantity threshold, re-optimizing the optical system parameters and / or sample model parameters of the second machine tool.

8. An optical measurement method, characterized in that, comprises the following steps: acquiring first spectral information and second spectral information of the same standard sample via a standard first machine tool and at least one non-standard second machine tool i, wherein the first machine tool and the second machine tool i are measuring machine tools of the same type, and the standard sample includes multiple measuring units j; Calculate the corresponding first film thickness parameter T_Ref according to the first spectral information j , and calculate the second film thickness parameter T_Meas of each measurement unit j according to the second spectral information ij , so as to respectively determine the first film thickness parameter T_Ref j and the second film thickness parameter T_Meas ij The thickness difference T_Diff in each measurement unit j ij ; Based on the absolute value of each of the thickness differences T_Diff ij screen the second machine i and the first machine Multiple target measurement units z with the largest detection deviation im ; According to the first film thickness parameter T_Ref of the multiple target measurement units z im and the optical system parameter SysParam of the second machine i j and / or the sample model parameter NK i i construct and solve the second spectral information about the multiple target measurement units z im ​​ Optimized equation, where the optimized equation is expressed as Adopt an optimization algorithm to fit the optical system parameters SysParam i and / or the sample model parameters NK i , to determine the optical system parameters SysParam_Fit im for correcting the detection deviation between the second machine stage i and the first machine stage at the multiple target measurement units z i and / or the sample model parameters NK_Fit i ; and detecting multiple samples to be measured in parallel via the first machine tool and at least one of the second machine tools i, respectively according to their corresponding optical system parameters and / or sample model parameters.

9. A computer-readable storage medium having computer instructions stored thereon, characterized in that, When the computer instructions are executed by a processor, the optical measurement method as claimed in claim 8 is implemented.

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