Elliptic polarization measuring system and measuring method

Abstract

The invention discloses an ellipsometry system and method which can be applied to the technical field of optics, and the system comprises a light path generation assembly, a sawtooth diaphragm, a separation assembly and a light path receiving assembly. The light path generation assembly is used for generating irradiation beams; the to-be-tested sample is used for reflecting the irradiation light beam and generating a signal light beam; the sawtooth diaphragm is arranged in an irradiation light path corresponding to the irradiation light beam, and is used for reducing the numerical aperture of the irradiation light beam and inhibiting the Filier diffraction; the separation assembly is arranged in a reflection light path corresponding to the signal light beam and is used for filtering diffraction stray light in the signal light beam and emitting effective irradiation light in the signal light beam to the light path receiving assembly; and the light path receiving assembly is used for receiving the effective irradiation light and determining optical information of the sample to be detected by using the effective irradiation light. Therefore, the numerical aperture of the irradiation light beam is reduced through the arrangement of the sawtooth diaphragm, and meanwhile, the light intensity distribution is modulated through the sawteeth, and the Filier diffraction is inhibited, so that the size of the irradiation light spot is reduced.

Description

Technical Field

[0001] The present application relates to the field of optical technologies, and particularly to an ellipsometry system and a measurement method. Background Art

[0002] Ellipsometry is used to detect film thickness, optical constants, and material microstructure, etc. As an ellipsometry instrument, the ellipsometer has become an extremely attractive measurement device due to its high measurement accuracy of film thickness and refractive index, non-contact with the sample, no damage to the sample, and no need for vacuum, etc.

[0003] The lateral resolution of the ellipsometer depends on the diameter of the illumination spot. Conventional ellipsometry systems usually change the focusing characteristics and propagation direction of the illumination beam by adjusting optical system parameters (such as the focal length, position of the lens, and the angle of the mirror), etc., so as to reduce the size and shape of the illumination spot. However, with the development of various technologies, the measurement area of the sample to be measured is getting smaller and smaller, while the accessory parameters in the conventional ellipsometry system are relatively limited, resulting in insufficient light intensity and small spots to meet the measurement requirements.

[0004] Therefore, how to reduce the size of the illumination spot is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] Based on the above problems, the present application provides an ellipsometry system and a measurement method. By setting a serrated aperture to reduce the numerical aperture of the illumination beam, and at the same time modulating the light intensity distribution by the serrations to suppress Fresnel diffraction, thereby reducing the size of the illumination spot.

[0006] In a first aspect, an embodiment of the present application provides an ellipsometry system, including: an optical path generating component, a serrated aperture, a separation component, and an optical path receiving component;

[0007] The optical path generating component is used to generate an illumination beam and obliquely irradiate the illumination beam onto the sample to be measured;

[0008] The sample to be measured is used to reflect the illumination beam and generate a signal beam;

[0009] The serrated aperture is arranged in the illumination optical path corresponding to the illumination beam, and is used to reduce the numerical aperture of the illumination beam, so that the illumination spot generated by the illumination beam on the sample to be measured is reduced, and Fresnel diffraction is suppressed;

[0010] The separation component is arranged in the reflection optical path corresponding to the signal beam, and is used to filter out the diffracted stray light in the signal beam and direct the effective illumination light in the signal beam to the optical path receiving component;

[0011] The optical path receiving component is used to receive the effective irradiation light and determine the optical information of the sample to be measured by using the effective irradiation light.

[0012] Optionally, the optical path generating component includes: a light source, an ellipsoidal reflector, and a field stop;

[0013] The ellipsoidal reflector is used to reflect the light emitted by the light source and focus it on the small hole of the field stop to generate an irradiation beam; the light source is a broadband light source; the light emitted by the broadband light source is in the ultraviolet to infrared band.

[0014] Optionally, the ellipsometer system further includes: a first broadband achromatic lens and a first polarizer;

[0015] The first broadband achromatic lens and the first polarizer are sequentially arranged in the optical path of the irradiation beam after the field stop;

[0016] The first polarizer is used to adjust the polarization state of the irradiation beam to form a polarized light spot on the sample to be measured.

[0017] Optionally, the optical path receiving component includes: a second broadband achromatic lens, a second polarizer, and a spectral detection module;

[0018] The second broadband achromatic lens, the second polarizer, and the spectral detection module are sequentially arranged in the optical path of the signal beam along the propagation direction of the signal beam.

[0019] Optionally, the second polarizer is a rotatable Glan-Taylor polarizing prism and serves as a rotating analyzer.

[0020] Optionally, the separation component includes a first part and a second part arranged in sequence along the circumferential direction. The first part is used to guide the effective irradiation light at the center of the signal beam to the spectral detection module in a reflection or transmission manner, and the second part is located outside the first part and is used to separate the diffracted stray light outside the signal beam from the effective irradiation light in a reflection or transmission manner.

[0021] Optionally, the optical path receiving component further includes: a beam splitting component; the spectral detection module includes: a first spectrometer and a second spectrometer; the first spectrometer is a first-band response wavelength spectrometer with a spectral resolution < 4 nm; the second spectrometer is a second-band response wavelength spectrometer with a spectral resolution < 8 nm; the wavelength in the first band is less than the wavelength in the second band;

[0022] The beam splitting component is arranged between the second polarizer and the separation component in the optical path of the signal beam, and is used to split the signal beam into a second signal sub-beam and a first signal sub-beam;

[0023] The first signal sub-beam is directed towards the first spectrometer;

[0024] The second signal sub-beam is directed towards the second spectrometer.

[0025] Optionally, the beam splitting component is a dot beam splitter, which is composed of a UV-grade fused silica substrate and an array of enhanced aluminum films evenly deposited on the fused silica substrate;

[0026] The incident angle of the signal beam on the beam splitting component is 45°.

[0027] Optionally, the separation component includes: a first filtering component and a second filtering component;

[0028] The first filtering component is used to filter the first signal sub-beam and filter out the first diffracted stray light in the first signal sub-beam; the wavelength band of the first diffracted stray light is the first wavelength band;

[0029] The second filtering component is used to filter the second signal sub-beam and filter out the second diffracted stray light in the second signal sub-beam; the wavelength band of the second diffracted stray light is the second wavelength band.

[0030] Optionally, the first filtering component includes a third part and a fourth part arranged in sequence along the circumferential direction. The third part is used to guide the effective irradiation light at the center of the first signal sub-beam to the first spectrometer in a reflective or transmissive manner. The fourth part is located outside the third part and is used to filter out the diffracted stray light outside the first signal sub-beam in a reflective or transmissive manner;

[0031] The second filtering component includes a fifth part and a sixth part arranged in sequence along the circumferential direction. The fifth part is used to guide the effective irradiation light at the center of the second signal sub-beam to the second spectrometer in a reflective or transmissive manner. The sixth part is located outside the fifth part and is used to filter out the diffracted stray light outside the second signal sub-beam in a reflective or transmissive manner.

[0032] Optionally, the first filtering component is composed of a first small-aperture diaphragm or a first mirror; when the first filtering component is the first small-aperture diaphragm, the third part is the first small aperture, and the fourth part is the first reflective film plated on the quartz substrate outside the first small aperture; when the first filtering component is the first mirror, the third part is the first reflective metal film plated in the middle, and the fourth part is the lens outside the first reflective metal film; the size of the first small aperture is the same as that of the first reflective metal film;

[0033] The second filtering component is composed of a second small-aperture diaphragm or a second mirror; when the second filtering component is the second small-aperture diaphragm, the fifth part is the second small aperture, and the sixth part is the second reflective film plated on the quartz substrate outside the second small aperture; when the second filtering component is the second mirror, the fifth part is the second reflective metal film plated in the middle, and the sixth part is the lens outside the second reflective metal film; the size of the second small aperture is the same as that of the second reflective metal film, and the size of the second small aperture is larger than that of the first small aperture.

[0034] In a second aspect, an embodiment of the present application provides a measurement method for an ellipsometry system, characterized in that the system includes an optical path generating component, a sawtooth aperture, a separation component, and an optical path receiving component, and the measurement method includes:

[0035] Configure the optical path generating component and the sawtooth aperture so that the irradiation beam generated by the optical path generating component can pass through the sawtooth aperture, irradiate the sample to be measured with the irradiation beam with a reduced numerical aperture, and generate a signal beam;

[0036] Use the separation component to filter out the diffracted stray light in the signal beam and direct the effective irradiation light in the signal beam to the optical path receiving component;

[0037] Use the optical path receiving component to determine the optical information of the sample to be measured according to the effective irradiation light.

[0038] It can be seen from the above technical solutions that compared with the prior art, the present application has the following advantages:

[0039] The ellipsometry system provided by this application includes: an optical path generation component, a sawtooth aperture, a separation component, and an optical path receiving component; the optical path generation component is used to generate an illumination beam; the sample to be measured is used to reflect the illumination beam and generate a signal beam; the sawtooth aperture is arranged in the illumination optical path corresponding to the illumination beam, and is used to reduce the numerical aperture of the illumination beam and suppress Fresnel diffraction. However, the tooth structure of the sawtooth aperture will generate petal-shaped diffracted stray light beside the effective illumination light; the separation component is arranged in the reflection optical path corresponding to the signal beam, and is used to filter out the diffracted stray light generated by the sawtooth aperture in the signal beam, and direct the effective illumination light in the signal beam to the optical path receiving component; the optical path receiving component is used to receive the effective illumination light and determine the optical information of the sample to be measured by using the effective illumination light. In this way, by setting the sawtooth aperture to reduce the numerical aperture of the illumination beam, and at the same time modulating the light intensity distribution by the sawtooth to suppress Fresnel diffraction, and filtering out the diffracted stray light generated by the sawtooth aperture through the separation component, the size of the illumination spot is reduced, and the influence of stray light on the test result is reduced. Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of an ellipsometry system provided by an embodiment of this application;

[0041] Figure 2 It is a schematic structural diagram of a sawtooth aperture provided by an embodiment of this application;

[0042] Figure 3 It is a schematic structural diagram of an optical path generation component provided by an embodiment of this application;

[0043] Figure 4 It is a schematic structural diagram of a beam adjustment component provided by an embodiment of this application;

[0044] Figure 5 It is a schematic diagram of chromatic focal shift provided by an embodiment of this application;

[0045] Figure 6 It is a schematic structural diagram of an optical path receiving component provided by an embodiment of this application;

[0046] Figure 7 It is a schematic structural diagram of an optical path receiving component with a beam splitting component provided by an embodiment of this application;

[0047] Figure 8 It is a schematic diagram of a small hole aperture of two different processes provided by an embodiment of this application;

[0048] Figure 9 It is a schematic structural diagram of a calibration module provided by an embodiment of this application;

[0049] Figure 10 It is a schematic structural diagram of a detector provided by an embodiment of this application;

[0050] Figure 11 Schematic diagram of another ellipsometry system provided by an embodiment of the present application;

[0051] Figure 12 Schematic diagram of an illumination spot provided by an embodiment of the present application;

[0052] Figure 13 Flowchart of a measurement method for an ellipsometry system provided by an embodiment of the present application;

[0053] Figure 14 PSF cross-sectional diagrams with and without a serrated aperture at different wavelengths provided by an embodiment of the present application;

[0054] Figure 15 Schematic diagram of the relationship between the sample height and the centroid of the light spot provided by an embodiment of the present application. Detailed implementation manners

[0055] As described above, the existing ellipsometry systems cannot obtain sufficient light intensity and small light spots to meet the measurement requirements. Specifically, the components of traditional ellipsometry systems are relatively fixed. To reduce the size and shape of the illumination spot, traditional ellipsometry systems usually adjust the focusing characteristics and propagation direction of the illumination beam by adjusting the parameters of the optical system (such as the focal length, position of the lens, and the angle of the mirror), so as to adjust the illumination spot. However, with the development of various technologies, the measurement area of the sample to be measured is getting smaller and smaller, and the parameters of the components in the traditional ellipsometry system are relatively limited, resulting in the inability to obtain sufficient light intensity and small light spots to meet the measurement requirements.

[0056] To solve the above problems, the present application provides an ellipsometry system, including: an optical path generating component, a serrated aperture, a separating component, and an optical path receiving component; the optical path generating component is used to generate an illumination beam; the sample to be measured is used to reflect the illumination beam and generate a signal beam; the serrated aperture is arranged in the illumination optical path corresponding to the illumination beam, and is used to reduce the numerical aperture of the illumination beam and suppress Fresnel diffraction. However, the tooth structure of the serrated aperture will generate petal-shaped diffracted stray light beside the effective illumination light. For this reason, the separating component is arranged in the reflection optical path corresponding to the signal beam, and is used to filter out the diffracted stray light generated by the serrated aperture in the signal beam, and direct the effective illumination light in the signal beam to the optical path receiving component; the optical path receiving component is used to receive the effective illumination light and determine the optical information of the sample to be measured by using the effective illumination light.

[0057] In this way, by setting a serrated aperture to reduce the numerical aperture of the illumination beam, modulating the light intensity distribution with the serrations at the same time to suppress Fresnel diffraction, and filtering out the diffracted stray light generated by the serrated aperture through the separating component, the size of the illumination spot is further reduced.

[0058] It should be noted that an ellipsometry system and a measurement method provided in this application can be applied to the field of optical technology. The above is only an example and does not limit the application field of the ellipsometry system and the measurement method provided in this application.

[0059] In order to make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0060] Figure 1 This is a schematic structural diagram of an ellipsometry system provided in an embodiment of this application. Combining Figure 1 As shown, an ellipsometry system 100 provided in an embodiment of this application includes: an optical path generating component 110, a sawtooth aperture 120, a separation component 130, and an optical path receiving component 140;

[0061] The optical path generating component 110 is configured to generate an irradiation beam and obliquely irradiate the irradiation beam onto the sample to be measured;

[0062] The sample to be measured is configured to reflect the irradiation beam and generate a signal beam;

[0063] The sawtooth aperture 120 is disposed in the irradiation optical path corresponding to the irradiation beam, and is configured to reduce the numerical aperture of the irradiation beam, reduce the irradiation spot generated by the irradiation beam on the sample to be measured, and suppress Fresnel diffraction;

[0064] The separation component 130 is disposed in the reflection optical path corresponding to the signal beam, and is configured to filter out the diffracted stray light in the signal beam and direct the effective irradiation light in the signal beam to the optical path receiving component 140;

[0065] The optical path receiving component 140 is configured to receive the effective irradiation light and determine the optical information of the sample to be measured by using the effective irradiation light.

[0066] Specifically, the specimen stage is set horizontally, and the specimen to be measured is placed on the specimen stage. The specimen stage can drive the specimen to be measured to move synchronously in the XYZ axes, and the adjustment accuracy is <1 μm. The optical path generation component 110 and the optical path receiving component 140 are respectively arranged obliquely above the specimen to be measured, and they are rotationally symmetrically arranged with respect to the specimen to be measured. The optical path generation component 110 can generate an irradiation beam, and the irradiation optical path formed by the beam is directed towards the specimen to be measured. In the embodiment of the present application, a sawtooth aperture stop 120 is arranged in the irradiation optical path. By means of the sawtooth aperture stop 120, the size of the irradiated geometric spot can be restricted, so that the light intensity of the irradiated spot is greater, and its sawteeth can modulate the light intensity distribution, thereby suppressing Fresnel diffraction and reducing the size of the diffraction spot. When the spot with reduced size irradiates the characteristic region of the specimen to be measured, through the interaction, the polarization state of the signal beam reflected from the specimen to be measured changes, thereby carrying the specimen information. However, the tooth structure of the sawtooth aperture stop will generate petal-shaped diffracted stray light beside the effective irradiated light. The separation component 130 is arranged in the reflection optical path corresponding to the signal beam, and can filter the diffracted stray light in the beam and guide the effective irradiated light in the beam to the optical path receiving component. In this way, when the optical path receiving component 140 receives the effective irradiated light, the optical information (broad-spectrum amplitude information) of the specimen to be measured can be analyzed and obtained through a spectrometer, thereby realizing the precise analysis of the small-size measurement area.

[0067] In addition, Figure 2 FIG. is a schematic structural diagram of a sawtooth aperture stop provided by an embodiment of the present application. As shown in Figure 2 FIG., the sawtooth aperture stop 120 generally has periodic fine teeth, and the fine teeth can be rectangular triangular, sinusoidal or other shapes. In the embodiment of the present application, the elliptical sawtooth aperture stop 120 ( Figure 2 a) can be used alone, and the rectangular sawtooth aperture stop 120 ( Figure 2 b) needs to be used in a vertical combination of two. When the sawtooth aperture stop 120 is located in front of the optical lens of the irradiation optical path, as a usable elliptical sawtooth aperture stop 120, its dimensions are: the X-direction aperture is 10 mm, triangular teeth, the bottom side length of the teeth is 0.3 mm, the tooth height is 4 mm, the Y-direction aperture is 6 mm, triangular teeth, the bottom side length of the teeth is 0.15 mm, and the tooth height is 2.5 mm.

[0068] Figure 3 FIG. is a schematic structural diagram of an optical path generation component provided by an embodiment of the present application. As shown in Figure 3 FIG., the optical path generation component 110 includes: a light source 111, an ellipsoidal reflector 112, and a field stop 113;

[0069] The ellipsoidal reflector 112 is used to reflect the light emitted by the light source 111 and focus it on the small hole of the field stop 113 to generate an irradiation beam; the light source 111 is a broad-spectrum light source 111; the light emitted by the broad-spectrum light source 111 is in the ultraviolet to infrared band.

[0070] Specifically, to meet the wide-spectrum requirement, the light source 111 adopted in the embodiments of the present application can emit light in the wavelength range of 185 nm - 2300 nm, and the light scatters in all directions. The light irradiated on the ellipsoidal mirror 112 will converge on the field stop 113. The field stop 113 in the embodiments of the present application is a small-hole stop. The ellipsoidal mirror 112 converges the light onto the small hole of the small-hole stop, and then the light diverges after passing through the small hole, forming a divergent light beam. The small-hole stop can be made by etching a small hole on a stainless-steel metal sheet. Generally, the small hole is a 40-μm round hole. It can be understood that the ellipsoidal mirror 112 can reduce the light loss of the light source 111, thereby increasing the light intensity of the light converging on the field stop 113. In other embodiments, it is not limited to the ellipsoidal mirror 112, and other devices can be used to achieve the functions of convergence and optical path adjustment, such as focusing lenses, mirrors, etc.

[0071] Figure 4 It is a schematic structural diagram of a beam adjustment component provided by the embodiments of the present application. Combining Figure 4 As shown, the beam adjustment component includes: a first wide-spectrum achromatic lens 150 and a first polarizer 160;

[0072] The first wide-spectrum achromatic lens and the first polarizer are sequentially arranged in the optical path of the irradiation beam after the field stop 113;

[0073] The first polarizer is used to adjust the polarization state of the irradiation beam and form a polarized light spot on the sample to be measured.

[0074] Specifically, in the beam adjustment component, the first polarizer 160 is arranged at the end farthest from the field stop 113. It can be a Glan-Taylor polarizing prism, whose function is to filter out the P light, so that the light beam incident on the sample to be measured is a linearly polarized light with only S light, and a polarized light spot is formed on the sample to be measured. The irradiation optical path lens can use a (first) wide-spectrum achromatic lens, which is arranged between the field stop 113 and the first polarizer 160. Figure 5 It is a schematic diagram of chromatic focal shift provided by the embodiments of the present application. Combining Figure 5 As shown, through achromatic design, the first wide-spectrum achromatic lens 150 can achieve a chromatic focal shift of 638 μm in the wavelength range of 185 nm - 2300 nm.

[0075] In addition, in the design of the beam adjustment component, the positional relationship between the serrated aperture 120 and the first wide-spectrum achromatic lens 150 can be selected according to the optical path modulation requirements. For example, the serrated aperture 120 can be located in front of the lens, in the lens, or behind the lens. Since in the ellipsometry optical path, the light beam incident on the sample is usually obliquely incident, the contour of the serrated aperture 120 can also change the ellipticity or the diameters of the two serrated apertures 120 according to the actual design.

[0076] Figure 6 This is a schematic structural diagram of an optical path receiving component provided by an embodiment of the present application. In combination with Figure 4 As shown, the optical path receiving component 140 includes: a second wide-spectrum achromatic lens 250, a second polarizer 260, and a spectral detection module 240;

[0077] The second wide-spectrum achromatic lens 250, the second polarizer 260, and the spectral detection module 240 are sequentially arranged in the optical path of the signal beam along the propagation direction of the signal beam.

[0078] Specifically, the second wide-spectrum achromatic lens 250 is symmetrically installed in the receiving optical path (the optical path of the signal beam) with respect to the first wide-spectrum achromatic lens 150, and the specifications of the second wide-spectrum achromatic lens 250 and the first wide-spectrum achromatic lens 150 are the same. The angle between the illumination optical path and the receiving optical path can be 90°, 120°, 130°, etc., which is specifically determined by the film material and thickness of the sample to be measured. The second wide-spectrum achromatic lens 250 and the second polarizer 260 are sequentially arranged in the optical path of the signal beam along the propagation direction of the signal beam. The second polarizer 260 can also be a Glan-Taylor polarizing prism. After the signal beam passes through the second polarizer 260, it becomes linearly polarized light and continues to propagate towards the separation component 130. It can be understood that due to the existence of the serrated aperture 120, there are diffracted stray light and effective illumination light in the signal beam. The separation component 130 can separate the diffracted stray light and the effective illumination light in the signal beam according to the different propagation properties of different lights, and then filter out the diffracted stray light, and only guide the effective illumination light to the spectral detection module 240.

[0079] As an implementation manner, regarding how to design the second polarizer 260, the second polarizer 260 is a rotatable Glan-Taylor polarizing prism and serves as a rotating analyzer.

[0080] Specifically, the second polarizer 260 is set as a rotatable Glan-Taylor polarizing prism. When measuring the sample to be measured, the measurement data can be increased by rotating the second polarizer 260.

[0081] As an implementation, regarding how to design the separation component 130, the separation component 130 includes a first part and a second part arranged sequentially in the circumferential direction. The first part is configured to guide the effective illumination light at the center of the signal beam to the spectral detection module 240 in a manner of reflection or transmission. The second part is located outside the first part and is configured to separate the diffracted stray light outside the signal beam from the effective illumination light in a manner of reflection or transmission. Further, the first part is configured to guide the effective illumination light at the center of the signal beam to the spectral detection module 240 in one of the ways of reflection and transmission, and the second part is configured to separate the diffracted stray light outside the signal beam from the effective illumination light in the other way of reflection and transmission. Wherein, the effective illumination light and / or the diffracted stray light transmitting through the separation component 130 may be that the light beam passes through a transparent medium (such as a lens) or through a hole.

[0082] Specifically, according to the positional relationship between the effective illumination light and the diffracted stray light in the signal beam and their respective covered illumination ranges, the separation component 130 in the optical path is correspondingly provided with different structures at different positions, that is, a first part and a second part arranged sequentially in the circumferential direction, so as to enable the first part and the second part to process the effective illumination light at the center of the signal beam and the diffracted stray light outside the signal beam respectively, filter out the diffracted stray light therein, and guide the effective illumination light to the spectral detection module 240.

[0083] Figure 7 It is a schematic structural diagram of an optical path receiving component with a beam splitting component provided by an embodiment of the present application. Combining Figure 7 As shown, the optical path receiving component 140 further includes: a beam splitting component 270; the spectral detection module 240 includes: a first spectrometer 241 and a second spectrometer 242; correspondingly, the separation component 130 includes: a first filtering component 131 and a second filtering component 132; the first spectrometer is a first band response wavelength spectrometer with a spectral resolution < 4 nm; the second spectrometer is a second band response wavelength spectrometer with a spectral resolution < 8 nm; the wavelength in the first band is less than the wavelength in the second band;

[0084] The beam splitting component 270 is arranged between the second polarizer 260 and the separation component 130 in the optical path of the signal beam, and is configured to divide the signal beam into a second signal sub-beam and a first signal sub-beam;

[0085] The first signal sub-beam is incident on the first spectrometer 241;

[0086] The second signal sub-beam is incident on the second spectrometer 242.

[0087] Specifically, the light source 111 provides light in the wavelength band of 185 nm - 2300 nm. Due to the relatively wide spectrum, in order to achieve wide-spectrum measurement and ensure the accuracy of measurement, two spectrometers with different response wavelengths can be respectively set to obtain wide-spectrum amplitude information. The beam splitting component 270 can split the signal beam into two parts (the second signal sub-beam and the first signal sub-beam), one part is directed to the first spectrometer 241, and the other part is directed to the second spectrometer 242. As an example, in this application, the optical path is set such that the first signal sub-beam is directed to the first spectrometer 241; the second signal sub-beam is directed to the second spectrometer 242. Among them, the first spectrometer 241 is a spectrometer with a response wavelength of 185 nm - 1200 nm (the first wavelength band), and the spectral resolution < 4 nm. Its function is to collect and analyze the spectral light intensity information in the 185 nm - 1200 nm (the second wavelength band) band at different rotation angles of the second polarizer 260. The second spectrometer 242 is a spectrometer with a response wavelength of 1200 nm - 2300 nm, and the spectral resolution < 8 nm. Its function is to collect and analyze the spectral light intensity information in the 1200 nm - 2500 nm band at different rotation angles of the second polarizer 260.

[0088] The first filtering component 131 is used to filter the first signal sub-beam and filter out the first diffracted stray light in the first signal sub-beam; the wavelength band of the first diffracted stray light is the first wavelength band;

[0089] The second filtering component 132 is used to filter the second signal sub-beam and filter out the second diffracted stray light in the second signal sub-beam; the wavelength band of the second diffracted stray light is the second wavelength band.

[0090] Specifically, the first spectrometer 241 can analyze the spectral light intensity information in the 185 nm - 1200 nm band. However, since the diffracted stray light (the first diffracted stray light) in the 185 nm - 1200 nm band (the first wavelength band) existing in the first signal sub-beam will affect the analysis result of the first spectrometer 241, it is necessary to set the corresponding first filtering component 131 to filter it. Similarly, in order to filter the diffracted stray light (the second diffracted stray light) in the 1200 nm - 2300 nm band in the second signal sub-beam, the second filtering component 132 is set in the embodiment of this application, and the diffracted stray light in the 1200 nm - 2300 nm band (the second wavelength band) is filtered out through the second filtering component 132.

[0091] As an implementation manner, regarding how to design the beam splitting component 270, the above beam splitting component 270 is a dot beam splitter, which is composed of a UV-grade fused silica substrate and an enhanced aluminum film lattice uniformly distributed on the fused silica substrate;

[0092] The incident angle of the signal beam on the beam splitting component 270 is 45°.

[0093] Specifically, the beam splitting component 270 in the embodiments of the present application is a dot beam splitter, which is formed by plating a uniformly distributed enhanced aluminum film lattice on a fused silica substrate of UV grade. In order to achieve uniform beam splitting, the signal beam can be incident on the beam splitting component 270 at an incident angle of 45°. The beam splitting component 270 reflects the light incident on the enhanced aluminum film lattice to form a second signal sub-beam that is incident on the second spectrometer 242; the light that is not incident on the enhanced aluminum film lattice is transmitted to form a first signal sub-beam that is incident on the first spectrometer 241. In other embodiments, it may not be limited to a dot beam splitter, and other devices can be used to achieve the beam splitting function, such as a semi-transmissive semi-reflective mirror, etc.

[0094] As an implementation manner, regarding how to design the first filtering component 131 and the second filtering component 132, the above-mentioned first filtering component 131 includes a third part and a fourth part that are sequentially arranged along the circumferential direction. The third part is used to guide the effective irradiation light at the center of the first signal sub-beam to the first spectrometer 241 in a reflective or transmissive manner. The fourth part is located outside the third part and is used to filter out the diffracted stray light outside the first signal sub-beam in a reflective or transmissive manner;

[0095] The second filtering component 132 includes a fifth part and a sixth part that are sequentially arranged along the circumferential direction. The fifth part is used to guide the effective irradiation light at the center of the second signal sub-beam to the second spectrometer 242 in a reflective or transmissive manner. The sixth part is located outside the fifth part and is used to filter out the diffracted stray light outside the second signal sub-beam in a reflective or transmissive manner.

[0096] Specifically, according to the positional relationship between the effective irradiation light in the first band and the diffracted stray light in the first signal sub-beam and their respective covered irradiation ranges, the first filtering component 131 in the optical path is correspondingly provided with different structures at different positions, that is, the third part and the fourth part that are sequentially arranged along the circumferential direction. Furthermore, the third part and the fourth part respectively process the effective irradiation light in the first band at the center of the first signal sub-beam and the diffracted stray light in the first band outside the first signal sub-beam, filter out the diffracted stray light therein, and guide the effective irradiation light to the first spectrometer 241. Similarly, based on the positions of the diffracted stray light in the first band and the second band and their respective covered irradiation ranges being different, the second filtering component 132 in the optical path is correspondingly provided with different structures at different positions, that is, the fifth part and the sixth part that are sequentially arranged along the circumferential direction. Furthermore, the fifth part and the sixth part respectively process the effective irradiation light in the second band at the center of the second signal sub-beam and the diffracted stray light in the second band outside the second signal sub-beam, filter out the diffracted stray light therein, and guide the effective irradiation light to the second spectrometer 242.

[0097] As an implementation manner, regarding how to design the first filtering component 131 and the second filtering component 132, the above-mentioned first filtering component 131 is composed of a first small-aperture diaphragm or a first mirror; when the first filtering component 131 is a first small-aperture diaphragm, the third part is a first small hole, and the fourth part is a first reflective film plated on the quartz substrate outside the first small hole; when the first filtering component 131 is a first mirror, the third part is a first reflective metal film plated in the middle, and the fourth part is a lens outside the first reflective metal film; the size of the first small hole is the same as that of the first reflective metal film; further, the sizes of the first small hole and the first reflective metal film are 60um * 120um;

[0098] Since the wavelength ranges from ultraviolet to infrared and there are few available glass material types, the achromatic lens cannot completely eliminate chromatic aberration. Therefore, the spot sizes on the first filtering component 131 and the second filtering component 132 are different. So, the sizes of the central small holes of the first filtering component 131 and the second filtering component 132 need to be determined according to the actual effective irradiation light size and the interval distance between the effective irradiation light and the diffracted stray light, so as to separate the effective irradiation light and the diffracted stray light in the signal beam.

[0099] The second filtering component 132 is composed of a second small-aperture diaphragm or a second mirror; when the second filtering component 132 is a second small-aperture diaphragm, the fifth part is a second small hole, and the sixth part is a second reflective film plated on the quartz substrate outside the second small hole; when the second filtering component 132 is a second mirror, the fifth part is a second reflective metal film plated in the middle, and the sixth part is a lens outside the second reflective metal film. The size of the second small hole is the same as that of the second reflective metal film, and the size of the second small hole is larger than that of the first small hole; further, the sizes of the second small hole and the second reflective metal film are 80um * 160um.

[0100] Figure 8 Schematic diagrams of small-aperture diaphragms of two different processes provided by the embodiments of the present application. Combined with Figure 8 As shown, the first filtering component 131 provided in the embodiment of the present application corresponds to the first spectrometer 241. The first filtering component 131 can be a first small-aperture diaphragm, such as Figure 8a. To filter the diffracted stray light in the wavelength band of 185 nm - 1200 nm, the first small aperture diaphragm is set as a mirror structure with a first reflective film deposited on a quartz substrate. Then, based on the different distances between the diffracted stray light in the wavelength band of 185 nm - 1200 nm and the effective irradiation light, and the different spot sizes of the effective irradiation light, a small hole with a size of 60 μm * 120 μm is etched in the center of the first reflective film in the mirror structure. After the first transmitted light irradiates the first small aperture diaphragm, its transmitted light filters out the diffracted stray light in the wavelength band of 185 nm - 1200 nm. Therefore, it irradiates the first spectrometer 241, and its reflected light is the diffracted stray light in the wavelength band of 185 nm - 1200 nm, which is filtered out. As another setting of the first filtering component 131, the first filtering component 131 can also be a mirror structure (the first mirror) with a small hole of 60 μm * 120 μm in the middle plated with a reflective metal film (the first reflective metal film) and the edge not plated, such as Figure 8 b. At this time, its transmitted light is the diffracted stray light in the wavelength band of 185 nm - 1200 nm, and its reflected light filters out the diffracted stray light in the wavelength band of 185 nm - 1200 nm. Therefore, it irradiates the first spectrometer 241. Similarly, the second filtering component 132 can also be composed of a second small aperture diaphragm or a second mirror. However, the distance between the diffracted stray light in the wavelength band of 185 nm - 1200 nm and the effective irradiation light is different from the distance between the diffracted stray light in the wavelength band of 1200 nm - 2300 nm and the effective irradiation light, and the spot size of its effective irradiation light is also different. For this reason, the small hole size of the second small aperture diaphragm is 80 μm * 160 μm, and a second reflective film is deposited on the quartz substrate outside the small hole. The second reflective metal film is plated in the middle of the second mirror, and the size of the second reflective metal film is 80 μm * 160 μm.

[0101] As an implementation manner, for how to design the ellipsometry system, the above ellipsometry system further includes: a calibration module 280;

[0102] The calibration module 280 is arranged in the optical path of the diffracted stray light, and is used to receive the diffracted stray light and determine the height information of the sample to be measured according to the diffracted stray light.

[0103] Figure 9 This is a schematic structural diagram of a calibration module provided by an embodiment of the present application. Combining Figure 9 As shown, the tooth structure of the sawtooth diaphragm will generate petal-shaped diffracted stray light beside the effective irradiation light. The separation component 130 can separate the diffracted stray light and the effective irradiation light in the signal beam. Among them, the effective irradiation light is used by the spectral detection module 240 for measurement and to determine the optical information of the sample to be measured. In addition, an embodiment of the present application can also set a calibration module 280 to use the separated diffracted stray light to calibrate the height position of the calibration sample online in-situ to improve the measurement accuracy.

[0104] As an implementation manner, regarding how to design the calibration module 280, the above-mentioned calibration module 280 includes: a first detector 281 and a second detector 282;

[0105] The first detector 281 is arranged in the optical path of the first diffracted stray light and is used to receive the first diffracted stray light in the first signal sub-beam;

[0106] The second detector 282 is arranged in the optical path of the second diffracted stray light and is used to receive the second diffracted stray light in the second signal sub-beam.

[0107] Figure 10 It is a schematic structural diagram of a detector provided by an embodiment of the present application. Combined with Figure 10 As shown, since the achromatic lens cannot completely eliminate chromatic aberration, there is chromatic aberration in the illumination spot, and the focal points of the illumination spots in the two bands of 185 - 1200 nm and 1200 nm - 2300 nm are inconsistent. The spot position information received by the first detector 281 and the second detector 282 can be used to calibrate the focal points of the two bands respectively, improving the measurement accuracy. The sample height accuracy can reach 0.2 um.

[0108] As an implementation manner, regarding how to increase the intensity of the diffracted stray light detected by the detector, the above-mentioned first reflective film is an ultraviolet-enhanced aluminum film, and the second reflective film is an infrared-enhanced silver film.

[0109] Specifically, compared with a general reflective film, the ultraviolet-enhanced aluminum film has a stronger ability to reflect the diffracted stray light in the 185 nm - 1200 nm band; compared with a general reflective film, the infrared-enhanced silver film has a stronger ability to reflect the diffracted stray light in the 1200 nm - 2300 nm band. In summary, since the first filtering component 131 corresponds to the first detector 281 and the first spectrometer 241, when the first filtering component 131 is a small-aperture diaphragm, the effective illumination light passes through the first small hole of 60 um * 120 um and irradiates the first spectrometer 241, and the diffracted stray light in the 185 nm - 1200 nm band is reflected by the ultraviolet-enhanced aluminum film plated on the quartz substrate and guided to the first detector 281. Similarly, the second filtering component 132 corresponds to the second detector 282 and the second spectrometer 242. When the second filtering component 132 is a small-aperture diaphragm, the effective illumination light passes through the second small hole of 80 um * 160 um and irradiates the second spectrometer 242, and the diffracted stray light in the 1200 nm - 2300 nm band is reflected by the infrared-enhanced silver film plated on the quartz substrate and guided to the second detector 282. As an implementation manner, regarding how to design the ellipsometry system, the above-mentioned ellipsometry system further includes: a first filter 291 and a first focusing mirror 292 correspondingly arranged with the first detector 281, and a second filter 391 and a second focusing mirror 392 correspondingly arranged with the second detector 282;

[0110] The first filter 291, the first condenser 292, and the first detector 281 are sequentially arranged in the optical path of the first diffracted stray light along the propagation direction of the first diffracted stray light;

[0111] The first filter 291 is a narrowband filter in the third band, and is used to limit the wavelength of the first diffracted stray light; the third band is within the first band;

[0112] The first condenser 292 is used to converge the first diffracted stray light with the limited wavelength onto the first detector 281;

[0113] The second filter 391, the second condenser 392, and the second detector 282 are sequentially arranged in the optical path of the second diffracted stray light along the propagation direction of the second diffracted stray light;

[0114] The second filter 391 is a narrowband filter in the fourth band, and is used to limit the wavelength of the second diffracted stray light; the fourth band is within the second band;

[0115] The second condenser 392 is used to converge the second diffracted stray light with the limited wavelength onto the second detector 282.

[0116] Figure 11 It is a schematic structural diagram of another ellipsometry system provided by an embodiment of the present application. In combination with Figure 11As shown, the first filter 291 and the first condenser lens 292 are used corresponding to the first detector 281. Since the light beam incident on the first detector 281 is diffracted stray light in the wavelength band of 185 nm - 1200 nm, in order to limit the wavelength of the light intensity converged onto the first detector 281 by the first condenser lens 292, the first filter 291 can be set as a narrowband filter with a wavelength of 550 ± 50 nm (the third wavelength band), thereby reducing the chromatic aberration effect of the condenser lens and improving the accuracy of measuring the height of the sample to be measured. The first condenser lens 292 is a double - cemented lens made of calcium fluoride and fused quartz, and is used to converge the diffracted stray light in the 550 ± 50 nm wavelength band after filtering onto the first detector 281, and then the first detector 281 obtains the height information of the sample to be measured. Similarly, the second filter 391 and the second condenser lens 392 are used corresponding to the second detector 282. Since the light beam incident on the second detector 282 is diffracted stray light in the wavelength band of 1200 nm - 2300 nm, in order to limit the wavelength of the light intensity converged onto the second detector 282 by the second condenser lens 392, the second filter 391 can be set as a narrowband filter with a wavelength of 2000 ± 100 nm (the fourth wavelength band). The second condenser lens 392 is the same as the first condenser lens 292, which is a double - cemented lens, and is used to converge the diffracted stray light in the 2000 ± 100 nm wavelength band after filtering onto the second detector 282, and then the second detector 282 obtains the height information of the sample to be measured.

[0117] Figure 12 This is a schematic diagram of an irradiation spot provided by an embodiment of the present application. Combining Figure 12 As shown, a is the irradiation spot on the sample to be measured in the 185 nm - 1200 nm wavelength band, b is the irradiation spot on the first small aperture diaphragm in the 185 nm - 1200 nm wavelength band, c is the irradiation spot on the sample to be measured in the 1200 nm - 2300 nm wavelength band, and d is the irradiation spot on the second small aperture diaphragm in the 1200 nm - 2300 nm wavelength band.

[0118] In addition, both the first small aperture diaphragm and the second small aperture diaphragm are installed obliquely at an angle of 45° relative to the light beam.

[0119] In summary, an ellipsometry system and a measurement method provided by the present application. The system includes: an optical path generation component, a serrated aperture, a separation component, and an optical path receiving component; the optical path generation component is used to generate an illumination beam; a sample to be measured is used to reflect the illumination beam and generate a signal beam; the serrated aperture is arranged in the illumination optical path corresponding to the illumination beam, and is used to reduce the numerical aperture of the illumination beam and suppress Fresnel diffraction; however, the tooth structure of the serrated aperture will generate petal-shaped diffracted stray light beside the effective illumination light. The separation component is arranged in the reflection optical path corresponding to the signal beam, and is used to filter out the diffracted stray light in the signal beam and direct the effective illumination light in the signal beam to the optical path receiving component; the optical path receiving component is used to receive the effective illumination light and determine the optical information of the sample to be measured by using the effective illumination light. In this way, by setting the serrated aperture to reduce the numerical aperture of the illumination beam, and at the same time modulating the light intensity distribution by the serrations to suppress Fresnel diffraction, thereby reducing the size of the illumination spot.

[0120] Figure 13 The flowchart of a measurement method for an ellipsometry system provided by an embodiment of the present application. In combination with Figure 13 As shown, in a measurement method for an ellipsometry system provided by an embodiment of the present application, the system includes an optical path generation component, a serrated aperture, a separation component, and an optical path receiving component. The corresponding measurement method includes:

[0121] S1301: Configure the optical path generation component and the serrated aperture so that the illumination beam generated by the optical path generation component can pass through the serrated aperture, irradiate the sample to be measured with the illumination beam with a reduced numerical aperture, and generate a signal beam.

[0122] In practical applications, a broadband light source (in the 185nm - 2300nm band) is configured in the optical path generation component, and a serrated aperture is also configured in the illumination optical path. Figure 14 The PSF cross-sectional view with and without a serrated aperture at different wavelength bands provided by an embodiment of the present application. In combination with Figure 14As shown, a is the cross-sectional view of the PSF of the non-serrated aperture in the range of 185 nm - 1200 nm, b is the cross-sectional view of the PSF of the serrated aperture in the range of 185 nm - 1200 nm, c is the cross-sectional view of the PSF of the non-serrated aperture in the range of 1200 nm - 2300 nm, and d is the cross-sectional view of the PSF of the serrated aperture in the range of 1200 - 2300 nm. It can be seen that whether in the wavelength range of 185 nm - 1200 nm or 1200 - 2300 nm, when a serrated aperture is configured in the illumination optical path, the size of the illumination spot is always smaller than that of the non-serrated aperture. Thus, by configuring a serrated aperture in the illumination optical path, the illumination beam passing through the serrated aperture obliquely irradiates the sample to be measured, and a small, highly bright elliptically polarized spot with a known polarization state can be generated on the sample to be measured. The small spot irradiates the characteristic region of the sample to be measured, and through the interaction, the polarization state of the reflected light changes, thereby generating a signal beam carrying the sample information of the sample to be measured, and the first reflected light is directed to the optical path receiving component.

[0123] S1302: Use the separation component to filter out the diffracted stray light in the signal beam, and direct the effective illumination light in the signal beam to the optical path receiving component.

[0124] In practical applications, since the distances between the diffracted stray light of different wavelengths and the effective illumination light are different, and the spot sizes of the effective illumination light are also different, the diffracted stray light and the effective illumination light can be separated by wavelength in two segments (185 nm - 1200 nm and 1200 - 2300 nm). The separation component can be a small aperture diaphragm of a specific size or a mirror. When the signal beam irradiates on the separation component, the separation component can separate the effective illumination light and the diffracted stray light in the signal beam, thereby filtering out the diffracted stray light in the signal beam and guiding the effective illumination light to the spectrometer.

[0125] S1303: Use the optical path receiving component to determine the optical information of the sample to be measured according to the effective illumination light.

[0126] In practical applications, a spectral detection module is configured in the light receiving component, and the broadband spectral amplitude information of the sample to be measured can be obtained according to the effective illumination light.

[0127] Figure 15 This is a schematic diagram showing the relationship between the sample height and the centroid of the light spot provided by the embodiment of the present application. Combining Figure 15As shown, the diffracted light generated by the fine teeth of the serrated aperture is reflected into the focusing lens, and the stray light at the sample to be measured is imaged onto the detector, thereby obtaining the position information of the diffracted stray light. Since the r height of the sample to be measured is different, the position of the diffracted stray light on the detector is different, thus realizing the in-situ focusing function. Since the positions of the illumination component and the light receiving component are relatively fixed, and the ellipsometry system should ensure that the surface of the sample to be measured is at the focal position of the objective lens during measurement. Therefore, when the focal position of the known illumination optical path is known, the height information of the sample to be measured determined by the calibration module can be used to adjust the height of the sample to be measured by the sample stage, so that the surface of the sample to be measured is at the focal position of the objective lens, and then more accurate broadband amplitude information of the sample to be measured can be obtained.

[0128] In summary, based on an ellipsometry system provided by the present application, the present application provides a measurement method for an ellipsometry system, including: First, configure an optical path generation component and a serrated aperture so that the illumination beam generated by the optical path generation component can pass through the serrated aperture, irradiate the sample to be measured with the illumination beam with a reduced numerical aperture, and generate a signal beam. Then, use a separation component to filter out the diffracted stray light in the signal beam, and direct the effective illumination light in the signal beam to the optical path receiving component. Finally, use the optical path receiving component to determine the optical information of the sample to be measured according to the effective illumination light. In this way, by setting a serrated aperture to reduce the numerical aperture of the illumination beam, and at the same time modulating the light intensity distribution by the serrations to suppress Fresnel diffraction, thereby reducing the size of the illumination spot.

[0129] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An ellipsometric measurement system, characterized in that: include: A light path generating component, a sawtooth aperture, a separation component and a light path receiving component; The optical path generating component is used to generate an irradiation light beam, and direct the irradiation light beam obliquely toward the sample to be tested; The sample to be tested is used to reflect the irradiation light beam and generate a signal light beam; The sawtooth diaphragm is arranged in the illumination light path corresponding to the illumination light beam, and is used to reduce the numerical aperture of the illumination light beam, so as to reduce the illumination spot generated by the illumination light beam on the sample to be measured, and suppress Fresnel diffraction; The separation component is arranged in the reflection light path corresponding to the signal light beam, and is used to filter out the diffracted stray light in the signal light beam, and direct the effective illumination light in the signal light beam to the light path receiving component; The optical path receiving component is used to receive the effective illumination light and determine the optical information of the sample to be tested using the effective illumination light.

2. The ellipsometric measurement system according to claim 1, characterized in that: The optical path generating assembly comprises: a light source, an ellipsoidal reflector and a field stop; The ellipsoid reflector is used to reflect the light emitted by the light source and focus it on the small hole of the field aperture to generate an irradiation light beam; the light source is a wide-spectrum light source; the light emitted by the wide-spectrum light source is in the ultraviolet to infrared band.

3. The ellipsometric measurement system according to claim 2, characterized in that: The ellipsometric measurement system further comprises: a first wide spectrum achromatic lens and a first polarizer; The first wide spectrum achromatic lens and the first polarizer are sequentially arranged after the field stop in the optical path of the illumination light beam; The first polarizer is used to adjust the polarization state of the irradiation light beam to form a polarized light spot on the sample to be tested.

4. The ellipsometric measurement system according to claim 1, characterized in that: The optical path receiving component includes: a second wide spectrum achromatic lens, a second polarizer and a spectrum detection module; The second wide-spectrum achromatic lens, the second polarizer, and the spectrum detection module are sequentially arranged in the optical path of the signal light beam along the propagation direction of the signal light beam.

5. The ellipsometric measurement system according to claim 4, characterized in that: The second polarizer is a rotatable Glan-Taylor polarizing prism, which acts as a rotating analyzer.

6. The ellipsometric measurement system according to claim 4, characterized in that: The separation component includes a first part and a second part which are arranged in sequence along the circumferential direction, the first part is used to guide the effective illumination light at the center of the signal light beam to the spectral detection module by reflection or transmission, and the second part is located outside the first part, and is used to separate the diffracted stray light outside the signal light beam from the effective illumination light by reflection or transmission.

7. The ellipsometric measurement system according to claim 4, characterized in that: The optical path receiving component also includes: a spectroscopic component; the spectrum detection module includes: a first spectrometer and a second spectrometer; the first spectrometer response is a first band response wavelength spectrometer, and the spectral resolution is less than 4nm; the second spectrometer is a second band response wavelength spectrometer, and the spectral resolution is less than 8nm; the wavelength in the first band is smaller than the wavelength in the second band; The beam splitting component is disposed between the second polarizer and the separation component in the optical path of the signal beam, and is used to split the signal beam into the first signal sub-beam and the second signal sub-beam; The first signal sub-beam is directed toward the first spectrometer; The second signal sub-beam is directed toward the second spectrometer.

8. The ellipsometric measurement system according to claim 7, characterized in that: The beam splitter component is a dot beam splitter, which is composed of a UV grade fused silica substrate and a reinforced aluminum film dot matrix evenly distributed on the fused silica substrate; The incident angle of the signal light beam on the beam splitter is 45°.

9. The ellipsometric measurement system according to claim 7, characterized in that: The separation assembly comprises: a first filter assembly and a second filter assembly; The first filter component is used to filter the first signal sub-beam to filter out the first diffracted stray light in the first signal sub-beam; the wavelength band of the first diffracted stray light is the first wavelength band; The second filter component is used to filter the second signal sub-beam to filter out the second diffraction stray light in the second signal sub-beam; the wavelength band of the second diffraction stray light is the second wavelength band.

10. The ellipsometric measurement system according to claim 9, characterized in that: The first filter assembly comprises a third part and a fourth part which are sequentially arranged along the circumferential direction, the third part is used to guide the effective irradiation light at the center of the first signal sub-beam to the first spectrometer by reflection or transmission, and the fourth part is located outside the third part and is used to filter out the diffracted stray light outside the first signal sub-beam by reflection or transmission; The second filtering assembly includes a fifth part and a sixth part which are arranged in sequence along the circumferential direction. The fifth part is used to guide the effective illumination light in the center of the second signal sub-beam to the second spectrometer by reflection or transmission, and the sixth part is located outside the fifth part and is used to filter out the diffraction stray light outside the second signal sub-beam by reflection or transmission.

11. The ellipsometric measurement system according to claim 10, characterized in that: The first filter component is composed of a first pinhole aperture or a first reflector; when the first filter component is the first pinhole aperture, the third part is the first pinhole, and the fourth part is the first reflective film plated on the quartz substrate outside the first pinhole; when the first filter component is the first reflector, the third part is the first reflective metal film plated in the middle, and the fourth part is the lens outside the first reflective metal film; the first pinhole has the same size as the first reflective metal film; The second filter component is composed of a second pinhole aperture or a second reflector; when the second filter component is the second pinhole aperture, the fifth part is the second pinhole, and the sixth part is the second reflective film coated on the quartz substrate outside the second pinhole; when the second filter component is the second reflector, the fifth part is the second reflective metal film coated in the middle, and the sixth part is the lens outside the second reflective metal film; the second pinhole is the same size as the second reflective metal film, and the size of the second pinhole is larger than the size of the first pinhole.

12. A measurement method for an ellipsometric measurement system, characterized in that: The system includes a light path generating component, a sawtooth aperture, a separation component and a light path receiving component, and the measuring method includes: The optical path generating component and the sawtooth aperture are configured so that the illumination light beam generated by the optical path generating component can pass through the sawtooth aperture, the illumination light beam with a reduced numerical aperture is irradiated onto the sample to be measured, and a signal light beam is generated; Using the separation component to filter out diffracted stray light in the signal light beam, and directing effective illumination light in the signal light beam toward the optical path receiving component; The optical path receiving component is used to determine the optical information of the sample to be tested according to the effective irradiation light.

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