Three-dimensional shape measurement method and measurement device

Abstract

The present invention provides a method for measuring a three-dimensional shape, comprising the following steps: (a) establishing a theoretical spectrum database corresponding to the contour structure of a sample model, wherein the theoretical spectrum database includes contour parameters of the sample model and theoretical spectra corresponding to the contour parameters; (b) using a first measurement method to measure a measurement area of ​​the sample, and obtaining a first type parameter of the sample in the measurement area, wherein the first type parameter is one of the contour parameters; (c) using a second measurement method to measure the measurement area of ​​the sample, and obtaining a measurement spectrum of the sample in the measurement area; (d) obtaining a theoretical spectrum corresponding to the first type parameter obtained in step (b) from the theoretical spectrum database; and (e) matching the measurement spectrum obtained in step (c) with the theoretical spectrum obtained in step (d), and using the contour parameters corresponding to the theoretical spectrum with the highest matching degree as the contour parameters of the sample. The method has the advantage of realizing accurate and rapid measurement of the three-dimensional shape of the sample.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to a three-dimensional shape measurement method and a measurement device. Background Art

[0002] At present, the three-dimensional morphology of a sample is measured by using the optical critical dimension measurement (OCD) technology, which is mainly based on the measurement of film thickness and uses the reflection of elliptically polarized light to obtain the microscopic morphology of the sample.

[0003] The advantages of optical critical dimension measurement technology are: 1. It uses optical methods for measurement, which is fast and conducive to improving the output speed (throughput); 2. It can realize long-term stability monitoring and measurement of the process by establishing a database (library); 3. The collected spectrum is convenient for offline analysis. However, it also has disadvantages: 1. For structures with a large aspect ratio, the critical dimension (CD) measurement accuracy is poor, that is, there are certain limitations in the critical dimension (CD) measurement of structures with a large aspect ratio; 2. The sensitivity of three-dimensional morphology measurement is low for thin film layers or structures with multiple overlapping film layers (interference between film layers); 3. It takes a long time to establish a measurement model.

[0004] Therefore, there is an urgent need for a three-dimensional topography measurement method and device that can overcome the above-mentioned shortcomings. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a three-dimensional shape measurement method and a measuring device, which can realize accurate and rapid measurement of the three-dimensional shape of a sample.

[0006] In order to solve the above problems, the present invention provides a method for measuring three-dimensional morphology, which includes the following steps: (a) establishing a theoretical spectrum database corresponding to the contour structure of a sample model, wherein the theoretical spectrum database includes contour parameters of the sample model and theoretical spectra corresponding to the contour parameters; (b) using a first measurement method to measure a measurement area of ​​the sample to obtain a first type parameter of the sample in the measurement area, wherein the first type parameter is one of the contour parameters; (c) using a second measurement method to measure the measurement area of ​​the sample to obtain a measurement spectrum of the sample in the measurement area; (d) obtaining a theoretical spectrum corresponding to the first type parameter obtained in step (b) from the theoretical spectrum database; and (e) matching the measurement spectrum obtained in step (c) with the theoretical spectrum obtained in step (d), and taking the contour parameters corresponding to the theoretical spectrum with the highest matching degree as the contour parameters of the sample.

[0007] Further, the first type parameter is a critical dimension of the sample.

[0008] Furthermore, the first measurement method is an X-ray imaging method, and the steps of measuring the sample using the X-ray imaging method are as follows: X-rays are incident on the measurement area of ​​the sample; the X-rays passing through the measurement area of ​​the sample are detected and converted into the first type parameters of the measurement area of ​​the sample.

[0009] Furthermore, the X-ray is incident on the measurement area of ​​the sample along a direction perpendicular to the sample.

[0010] Furthermore, the second measurement method is an optical critical dimension measurement method, and the steps of measuring the sample using the optical critical dimension measurement method are as follows: elliptically polarized light is incident on the measurement area of ​​the sample, and the elliptically polarized light is reflected by the sample to form reflected light; the reflected light is collected to obtain a measurement spectrum of the measurement area of ​​the sample.

[0011] Furthermore, the elliptically polarized light is incident on the measurement area of ​​the sample at a preset inclination angle.

[0012] Furthermore, the measurement method further comprises the following steps: moving the sample to change the measurement area; and repeating steps (b) to (e).

[0013] The present invention also provides a measuring device for implementing the above-mentioned measuring method, which includes: a sample carrier for carrying a sample, and the sample carrier can rotate and move; a first measuring component for implementing the first measuring method; a second measuring component for implementing the second measuring method; a processor for storing a theoretical spectrum database, obtaining a first type parameter of a measuring area of ​​the sample according to the measurement result of the first measuring component, obtaining a measured spectrum of the measuring area of ​​the sample according to the measurement result of the second measuring component, and matching the measured spectrum with the theoretical spectrum corresponding to the first type parameter to obtain contour parameters of the measuring area of ​​the sample, and then obtaining the three-dimensional morphology of the measuring area of ​​the sample.

[0014] Furthermore, the first measurement method is an X-ray imaging method, and the first measurement component includes: an X-ray source, arranged above the sample carrier, for generating X-rays that are incident on a measurement area of ​​the sample; at least one X-ray transmission light receiver, arranged below the measurement area of ​​the sample, for receiving X-rays that pass through the sample and converting them into electrical signals, which are transmitted to the processor, and the processor obtains a first type parameter of the measurement area of ​​the sample based on the electrical signals.

[0015] Furthermore, the sample carrier includes a chuck and a base, the chuck is arranged on the base, the chuck is used to place the sample, the X-ray transmission light receiver is arranged on the base, and the X-ray transmission light receiver is not in contact with the sample.

[0016] Furthermore, the X-ray transmission light receiver includes a plurality of energy receiving areas with different sensitivities.

[0017] Furthermore, the second measurement method is an optical critical dimension measurement method, and the second measurement component includes: a light source, which is arranged above the sample carrier and is used to generate elliptically polarized light that is incident on a measurement area of ​​the sample; a detector, which is used to receive and detect the intensity of the reflected light of the sample, and convert it into an electrical signal, and transmit it to the processor, and the processor obtains a measurement spectrum of the measurement area of ​​the sample based on the electrical signal.

[0018] The advantage of the present invention is that the two measurement methods are combined to achieve accurate and rapid measurement of the three-dimensional morphology of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the steps of a specific implementation method of the three-dimensional topography measurement method of the present invention;

[0020] Figure 2 is a schematic structural diagram of a sample measured by the three-dimensional topography measurement method of the present invention;

[0021] Figure 3 It is a schematic structural diagram of a specific implementation of the measuring device of the present invention. DETAILED DESCRIPTION

[0022] The specific implementation of the three-dimensional shape measurement method and measurement device provided by the present invention is described in detail below with reference to the accompanying drawings.

[0023] A specific implementation of the three-dimensional morphology measurement method of the present invention is based on an optical key dimension measurement method and combined with an X-ray imaging method to obtain the three-dimensional morphology of a sample.

[0024] The basic working principle of the optical critical dimension measurement method (OCD) can be described as follows: (1) Establish a theoretical spectrum database corresponding to the contour structure of the sample model; (2) Obtain the measured spectrum of the sample through the optical critical dimension measurement device; (3) Find the characteristic spectrum that best matches the measured spectrum from the theoretical spectrum database to determine the profile parameters of the sample. The disadvantages of using the optical critical dimension measurement method to measure the three-dimensional morphology of the sample are: (1) The CD measurement accuracy is poor for structures with a large aspect ratio; (2) The sensitivity is low for thin film layers.

[0025] In view of the above-mentioned shortcomings of the optical critical dimension measurement method, the inventors found that by using the optical critical dimension measurement method to measure the measurement spectrum of the sample, using other methods to measure the CD of the sample, and then using CD as a known value and the measurement spectrum as a reference point to find the characteristic spectrum that best matches the measurement spectrum from the theoretical spectrum database, the measurement efficiency can be guaranteed while improving the measurement accuracy. CD is the abbreviation of Critical Dimension in English, and its Chinese abbreviation is critical dimension. In the integrated circuit photomask manufacturing and photolithography process, CD is a parameter that reflects the width of the characteristic lines of the integrated circuit in order to evaluate the accuracy of graphic processing. For example, CD is the line width or the width of the opening.

[0026] Figure 1 is a schematic diagram of the steps of a specific implementation method of the three-dimensional topography measurement method of the present invention, Figure 2 is a schematic diagram of the structure of a sample measured by the three-dimensional topography measurement method of the present invention, wherein the sample 30 has multiple dielectric layers. Figure 2 Schematically depicting a first dielectric layer 32 and a second dielectric layer 33 , during the process, openings 31 are formed in the first dielectric layer 32 and the second dielectric layer 33 .

[0027] See also Figure 1 and Figure 2 , the three-dimensional shape measurement method comprises the following steps:

[0028] Step S10, establishing a theoretical spectrum database corresponding to the profile structure of the sample model, wherein the theoretical spectrum database includes profile parameters of the sample model and theoretical spectra corresponding to the profile parameters.

[0029] In this step, a theoretical spectrum database corresponding to the contour structure of the sample model can be established by a modeling method. Specifically, the sample model is constructed according to the structural information of the process, and the structural information includes but is not limited to the film layer stacking information, geometric shape information and film layer optical properties, etc.; the theoretical spectrum corresponding to the sample model is calculated by numerical calculation and other methods.

[0030] The profile parameters include, but are not limited to, one or more of CD (opening width or line width), side wall angle, depth, and film layer height of the sample model in the measurement area. In this specific embodiment, the profile parameters include the width W, side wall angle α, depth D, height H1 of the first dielectric layer 32, and height H2 of the second dielectric layer 33 of the sample model in the measurement area.

[0031] Step S11, using a first measurement method to measure a measurement area of ​​the sample to obtain a first type parameter of the sample in the measurement area, where the first type parameter is one of the profile parameters.

[0032] In the present invention, a measurement method with high measurement accuracy for the first type of parameter is used to obtain the first type of parameter. In this specific embodiment, the first measurement method is an X-ray imaging method. The X-ray imaging method has high CD measurement accuracy for structures with a large aspect ratio and has a strong density resolution. The first type of parameter is CD, and in this specific embodiment, the CD is the width W of the opening 31.

[0033] The steps of measuring the measurement area C of the sample using the X-ray imaging method are as follows:

[0034] (a) X-rays are incident on the measurement area C of the sample 30 . The measurement area C of the sample 30 is located within the incident range of the X-rays, or the incident spot formed by the X-ray source is the measurement area C of the sample 30 .

[0035] The setting of the measurement area C can be set according to actual conditions. For example, for a sample, it can include multiple measurement points, and each measurement point can be used as a measurement area. If multiple measurement points need to be measured, after measuring one measurement point, the next measurement point can be measured using the measurement method of the present invention. If only one measurement point needs to be measured, only the measurement point can be measured, and other measurement points can be ignored.

[0036] Furthermore, in this specific embodiment, the X-rays are incident on the sample 30 in a direction perpendicular to the sample surface, that is, the X-rays are incident on the surface of the sample 30 at a vertical angle, which can increase the vertical transmission intensity and is beneficial to improving the sensitivity of the signal.

[0037] (b) detecting X-rays passing through the measurement region of the sample and converting the X-rays into first type parameters of the measurement region of the sample.

[0038] After the X-rays are incident on the measurement area of ​​the sample, they will penetrate the sample. In this step, the X-rays that penetrate the sample are detected, and the first type parameters of the measurement area of ​​the sample are obtained based on the energy of the transmitted X-rays.

[0039] In step S11, the first type parameters obtained in a measurement area may include multiple ones, and the average value of the multiple first type parameters is taken as the first type parameter obtained in this step.

[0040] Step S12: measuring the measurement area C of the sample using a second measurement method to obtain a measurement spectrum of the sample in the measurement area C.

[0041] In this step, the measurement spectrum is obtained by an optical measurement method. In this specific embodiment, the second measurement method is an optical critical dimension measurement method.

[0042] The steps of measuring the measurement area C of the sample using the optical critical dimension measurement method are as follows:

[0043] (a) Elliptically polarized light is incident on the measurement area C of the sample, and the elliptically polarized light is reflected by the sample to form reflected light.

[0044] The measurement area C is the same as the measurement area C in step S11. Further, the elliptically polarized light is incident on the measurement area C of the sample at a preset inclination angle. Preferably, the elliptically polarized light is incident on the measurement area C of the sample 30 in the direction of the Brewster angle of the sample, so that the reflected light is linearly polarized light, and its vibration direction is perpendicular to the incident plane.

[0045] (b) collecting the reflected light to obtain a measurement spectrum of the measurement area C of the sample.

[0046] In this step, the reflected light is collected and the light intensity of the reflected light is obtained, so that the measurement spectrum of the measurement area C of the sample can be obtained.

[0047] Step S13, acquiring a theoretical spectrum corresponding to the first type of parameters obtained in step S11 from the theoretical spectrum database.

[0048] In this step, the first type parameter obtained in step S11 is used as a known parameter, and a theoretical spectrum corresponding to the first type parameter is searched from the theoretical spectrum database. In this step, due to the influence of other parameters in the profile parameter, the number of theoretical spectra corresponding to the known first type parameter may be multiple, and in this step, multiple theoretical spectra are used as reference spectra for subsequent steps.

[0049] Step S14, matching the measured spectrum obtained in step S12 with the theoretical spectrum obtained in step S13, and taking the theoretical spectrum with the highest matching degree as the characteristic spectrum of the measurement area of ​​the sample, and the profile parameters corresponding to the characteristic spectrum are the profile parameters of the sample.

[0050] There may be multiple theoretical spectra obtained in step S13, so in step S14, a theoretical spectrum that best matches the measured spectrum is obtained from the multiple theoretical spectra. In this step, matching can be performed based on characteristic values ​​of the measured spectrum and the theoretical spectrum, and the characteristic values ​​include but are not limited to peak position and peak width.

[0051] The three-dimensional morphology of the sample can be obtained by obtaining the contour parameters of the sample. Furthermore, after obtaining the contour parameters of the sample, a three-dimensional morphology simulation diagram of the sample can be obtained according to the contour parameters.

[0052] Furthermore, if the sample is divided into a plurality of measurement areas, the measurement method further comprises the following steps: moving the sample, changing the measurement area C of the sample, and repeating steps S11 to S14. Specifically, the sample is moved in the X direction, the Y direction, or the Z direction, and the area of ​​the sample where the measurement has been completed is moved to the non-measurement range of the first measurement method and the second measurement method, and the measurement area of ​​the sample where the measurement has not been completed is moved to the measurement range of the first measurement method and the second measurement method.

[0053] The optical critical dimension measurement method has a fast measurement speed, the spectrum is easy to store and analyze, and there are mature technologies and analysis methods, but this method has certain limitations in measuring the line width parameters of structures with a large aspect ratio; X-rays have good accuracy in measuring the line width parameters of structures with a large aspect ratio due to their strong penetration, but their measurement speed is slow and the measurement environment requirements are high. In this specific embodiment, the CD parameters of the sample are measured by an X-ray imaging method, and the spectrum measured by the optical critical dimension measurement method is used. The CD parameters and the spectrum are used as reference points to find the characteristic spectrum that best matches the measured spectrum from the theoretical spectrum database, which can improve the measurement accuracy while ensuring the measurement efficiency, and obtain the three-dimensional morphology of the sample. This measurement method overcomes the shortcomings of the optical critical dimension measurement method for poor CD measurement accuracy, and also avoids the shortcomings of the X-ray imaging method for slow measurement speed and high measurement environment requirements, and can achieve accurate and fast measurement of the three-dimensional morphology of the sample.

[0054] The present invention also provides a measuring device for implementing the above-mentioned measuring method. Figure 3 is a schematic diagram of the structure of a specific embodiment of the measuring device of the present invention. Figure 3 The measuring device includes a sample stage 20, a first measuring component 21, a second measuring component 22 and a processor 23. Figure 3 In the figure, the dotted arrows are used to schematically illustrate the measurement path of the first measurement component 21, and the solid arrows are used to schematically illustrate the measurement path of the second measurement component 22.

[0055] The sample carrier 20 is used to carry a sample 30. In this specific embodiment, the sample carrier 20 includes a chuck 201 and a base 202. The chuck 201 is disposed on the base 202, and the chuck 201 is used to place the sample 30. After the sample 30 is placed on the chuck 201, the sample 30 does not contact the surface of the base 202, that is, the sample 30 is suspended above the base 202.

[0056] The sample stage 20 can move and rotate to drive the sample 30 to move and rotate, so as to facilitate the measurement component to measure the sample 30. Specifically, the sample stage 20 can move in the X direction, the Y direction and the Z direction, and can rotate with the axis perpendicular to the sample 30 as the rotation axis, thereby driving the sample 30 disposed on the sample stage 20 to move and rotate.

[0057] The first measurement component 21 is used to implement a first measurement method. In this specific embodiment, the first measurement method is an X-ray imaging method, and the first measurement component 21 is used to implement the X-ray imaging method to measure the sample 30. The first measurement component 21 includes an X-ray source 210 and at least one X-ray transmission light receiver 211.

[0058] The X-ray source 210 is disposed above the sample stage 20, and is used to emit X-rays incident on the sample 30. Preferably, the X-ray source 210 is disposed above the sample stage 20 in a direction perpendicular to the surface of the sample 30, that is, the X-ray source 210 is disposed directly above the sample 30 in a direction perpendicular to the surface of the sample 30, so as to ensure that the X-rays emitted by it can be vertically incident on the measurement area C of the sample 30.

[0059] The X-ray transmission light receiver 211 is disposed below the measurement area C of the sample 30, and is used to receive the X-rays transmitted through the sample 30 and convert them into electrical signals, which are transmitted to the processor 23, and the processor 23 obtains the first type parameter of the measurement area C of the sample according to the electrical signal. In this specific embodiment, the processor 23 obtains the CD of the measurement area C of the sample according to the electrical signal.

[0060] In this specific embodiment, the X-ray transmission light receiver 211 is arranged on the base 202, and the X-ray transmission light receiver 211 is not in contact with the sample 30. Further, the X-ray transmission light receiver 211 includes a plurality of energy receiving areas with different sensitivities, and the plurality of energy receiving areas are arranged in ascending order with a certain energy step length to increase the sensitivity of the X-ray transmission light receiver 211. For example, if it is determined that the energy range of the X-rays passing through the sample in the measurement area is 90ev-110ev, then every 2ev is used as a step length, and then we need 10 energy receiving areas to receive the signal in this energy range, which is conducive to setting the energy range of the received signal and can improve the sensitivity of the signal. Further, the X-ray transmission light receiver 211 includes but is not limited to a light sensor.

[0061] The second measurement component 22 is used to implement a second measurement method. In this specific embodiment, the second measurement method is an optical critical dimension measurement method, and the second measurement component 22 can implement the optical critical dimension measurement method to measure the sample 30. The second measurement component 22 includes a light source 220 and a detector 221.

[0062] The light source 220 is arranged above the sample stage 20, and is used to generate linear polarized light incident on the sample 30. In this specific embodiment, the light source 220 can pass through a polarizer 222, and the polarizer 222 has built-in optical devices such as a rochon prism to generate elliptically polarized light. The elliptically polarized light emitted by the light source 220 is reflected by the sample 30 to form a reflected light. In this specific embodiment, the light source 220 is arranged in the direction of the Brewster angle of the sample 30, so that the reflected light is linearly polarized light, and its vibration direction is perpendicular to the incident surface.

[0063] Furthermore, the light source 220 can be moved up and down to change the incident angle of the light source 220 onto the sample, so that a suitable incident angle can be selected according to actual measurement requirements.

[0064] The detector 221 is used to receive and detect the intensity of the reflected light of the sample 30 and convert it into an electrical signal, which is transmitted to the processor 23. The processor 23 obtains the measurement spectrum of the measurement area C of the sample according to the electrical signal.

[0065] Furthermore, the detector 221 further includes a polarizer 223 before it, and the polarizer 223 is used to collect polarized light with a specific polarization direction.

[0066] The processor 23 is used to store a theoretical spectrum database, obtain a first type parameter of the measurement area of ​​the sample according to the measurement result of the first measurement component 21, obtain a measurement spectrum of the measurement area of ​​the sample according to the measurement result of the second measurement component 22, and match the measurement spectrum with the theoretical spectrum corresponding to the first type parameter to obtain contour parameters of the measurement area of ​​the sample, and then obtain a three-dimensional morphology of the measurement area of ​​the sample.

[0067] Furthermore, in this specific implementation, the processor 23 is a processor used in the optical critical dimension measurement method in the prior art.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for measuring three-dimensional topography, characterized in that: The steps include: (a) establishing a theoretical spectrum database corresponding to the profile structure of the sample model, wherein the theoretical spectrum database includes profile parameters of the sample model and theoretical spectra corresponding to the profile parameters; (b) measuring a measurement area of ​​the sample using a first measurement method to obtain a first type parameter of the sample in the measurement area, where the first type parameter is a critical dimension of the sample; the first measurement method is an X-ray imaging method, and the steps of measuring the sample using the X-ray imaging method are as follows: X-rays are incident on the measurement area of ​​the sample, and an X-ray transmission light receiver is arranged below the measurement area of ​​the sample, and is used to receive the X-rays transmitted through the sample and convert them into electrical signals, and the electrical signals are transmitted to a processor, and the processor obtains a first type parameter of the measurement area of ​​the sample according to the electrical signals; the X-ray transmission light receiver includes a plurality of energy receiving areas with different sensitivities, and the plurality of energy receiving areas are arranged in ascending order with a certain energy step length, so as to increase the sensitivity of the X-ray transmission light receiver; (c) using a second measurement method to measure a measurement area of ​​the sample to obtain a measurement spectrum of the sample in the measurement area, wherein the second measurement method is an optical critical dimension measurement method, and the steps of measuring the sample using the optical critical dimension measurement method are as follows: Elliptically polarized light is incident on a measurement area of ​​the sample, and the elliptically polarized light is reflected by the sample to form reflected light; the reflected light is collected to obtain a measurement spectrum of the measurement area of ​​the sample; (d) acquiring a theoretical spectrum corresponding to the first type of parameters obtained in step (b) from the theoretical spectrum database; (e) matching the measured spectrum obtained in step (c) with the theoretical spectrum obtained in step (d), and taking the profile parameters corresponding to the theoretical spectrum with the highest matching degree as the profile parameters of the sample.

2. The three-dimensional shape measuring method according to claim 1, characterized in that: The X-rays are incident on the measurement region of the sample in a direction perpendicular to the sample.

3. The method for measuring three-dimensional shape according to claim 1, characterized in that: The elliptically polarized light is incident on the measurement area of ​​the sample at a preset inclination angle.

4. The three-dimensional shape measuring method according to claim 1, characterized in that: The measuring method further comprises the following steps: Move the sample to change the measurement area; Repeat steps (b) to (e).

5. A measuring device for implementing the measuring method according to any one of claims 1 to 4, characterized in that: include: A sample carrier, used to carry the sample, and the sample carrier can rotate and move; A first measurement component, used to implement a first measurement method; A second measurement component, used to implement a second measurement method; The processor is used to store a theoretical spectrum database, obtain a first type parameter of the measurement area of ​​the sample according to the measurement result of the first measurement component, obtain a measurement spectrum of the measurement area of ​​the sample according to the measurement result of the second measurement component, and match the measurement spectrum with a theoretical spectrum corresponding to the first type parameter to obtain a contour parameter of the measurement area of ​​the sample, thereby obtaining a three-dimensional morphology of the measurement area of ​​the sample.

6. The measuring device according to claim 5, characterized in that The first measurement method is an X-ray imaging method, and the first measurement component includes: An X-ray source, disposed above the sample stage, for generating X-rays incident on a measurement area of ​​the sample; At least one X-ray transmission light receiver is arranged below the measurement area of ​​the sample, and is used to receive the X-rays transmitted through the sample and convert them into electrical signals. The electrical signals are transmitted to the processor, and the processor obtains the first type parameter of the measurement area of ​​the sample according to the electrical signals.

7. The measuring device according to claim 6, characterized in that The sample carrier comprises a chuck and a base, wherein the chuck is arranged on the base and is used to place a sample, and the X-ray transmission light receiver is arranged on the base, and the X-ray transmission light receiver is not in contact with the sample.

8. The measuring device according to claim 6, characterized in that The X-ray transmission light receiver includes a plurality of energy receiving areas with different sensitivities.

9. The measuring device according to any one of claims 5 to 8, characterized in that: The second measurement method is an optical critical dimension measurement method, and the second measurement component includes: a light source, disposed above the sample stage, for generating elliptically polarized light incident on a measurement area of ​​the sample; The detector is used to receive and detect the intensity of the reflected light of the sample, convert it into an electrical signal, and transmit it to the processor. The processor obtains the measurement spectrum of the measurement area of ​​the sample according to the electrical signal.

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