Optical system

Abstract

The utility model provides an optical system, which comprises a collecting mirror suitable for collecting signal light generated by irradiating an incident light beam on the surface of a sample; a detector; the transmission compensation assembly is located in a light path between the collecting mirror and the detector, and the transmission compensation assembly comprises a transmitter used for splitting the signal light from the collecting mirror into transmission split beams; and the compensating mirror is used for carrying out optical path difference compensation on the transmission split beam. The optical detection system can compensate the optical path difference of the light beam so as to improve the quality of the light beam.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, in particular to an optical system. Background Art

[0002] During the optical inspection process, the light beam emitted by the light source needs to be split or combined. Current optical inspection equipment often uses a beam splitter to split or combine the light beam. However, due to the asymmetry of the beam splitter, the optical path difference of the light beam will change, resulting in a deterioration in the quality of the output light beam. Utility Model Content

[0003] An object of the embodiments of the present disclosure is to provide an optical system for improving light beam quality.

[0004] The utility model provides an optical system, comprising: a collecting mirror, suitable for collecting signal light generated by an incident light beam irradiating the surface of a sample; a detector; a transmission compensation component, located in the optical path between the collecting mirror and the detector, the transmission compensation component comprising: a transmitter, used for splitting the signal light from the collecting mirror into a transmission beam; and a compensation mirror, used for compensating for the optical path difference of the transmission beam.

[0005] Optionally, for the signal light emitted from the same collecting mirror in different directions, the longer the optical path of the signal light in the transmitter, the shorter the optical path in the compensation mirror.

[0006] Optionally, the transmissive device and the compensating mirror have the same structure.

[0007] Optionally, the compensation mirror and the transmitter are mirror-symmetrical about a reference plane, and the reference plane is perpendicular to a propagation direction of light passing through the optical axis of the collecting mirror in the transmission beam split between the transmitter and the compensation mirror.

[0008] Optionally, the compensation mirror is a wedge-shaped mirror, and the thickness of the compensation mirror decreases from the side where the optical path of the signal light in the transmitter is the smallest to the side where the optical path is the largest.

[0009] Optionally, the compensating mirror is a wedge-shaped mirror, and the wedge-shaped mirror is also used to separate light beams of different wavelengths.

[0010] Optionally, there are multiple collecting mirrors, and different collecting mirrors are used to collect signal light from different directions of the surface of the sample.

[0011] Optionally, the optical system also includes: a support table; a portion of the collecting mirrors is a reflective collecting mirror, and another portion of the collecting mirrors is a focusing collecting mirror; the orthographic projection of the reflective collecting mirror on the surface of the support table is located around the side of the orthographic projection of the focusing collecting mirror on the surface of the support table.

[0012] Optionally, it also includes: a light source, which is suitable for incident illumination light on the sample, and the sample is suitable for reflecting the illumination light to form the signal light; the illumination lights of different wavelengths generated by the light source are combined into a beam of illumination light and irradiated to the sample; or, the illumination lights of different wavelengths generated by the light source are irradiated to the sample at different incident angles.

[0013] Optionally, the signal light includes light beams of different wavelengths, and the transmitter is a dichroic mirror, a wavelength filter or a dispersion prism; or, the transmitter is an energy beam splitter or a polarization beam splitter.

[0014] Optionally, the transmitter is further used to separate another portion of light from the transmitted beam to form additional signal light; the detector includes: a first sub-detector and a second sub-detector, the first sub-detector is used to detect the transmitted beam, and the second sub-detector is used to detect the additional signal light.

[0015] Optionally, there are multiple transmission compensation components, including a first transmission compensation component and a second transmission compensation component; there are one or more detectors, including a first detector and a second detector; the optical system also includes: a separation mirror, which is used to separate the signal light of different angles collected by the collecting mirror and converge them to the first detector and the second detector respectively; the first transmission compensation component is located in the optical path between the separation mirror and the first detector; the second transmission compensation component is located in the optical path between the separation mirror and the second detector.

[0016] The optical system provided by the present invention includes a collecting mirror, a detector, and a transmission compensation assembly. The collecting mirror is adapted to collect signal light generated by an incident light beam irradiating the surface of a sample. The transmission compensation assembly is located in the optical path between the collecting mirror and the detector. The transmission compensation assembly includes a transilluminator for splitting the signal light from the collecting mirror into a transmission beam, and a compensation mirror for compensating for the optical path difference of the transmission beam, thereby reducing the optical path difference between the light rays in the transmission beam caused by the transilluminator. This reduces the optical path difference between the light rays in the transmission beam detected by the detector, thereby improving the beam quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic structural diagram of an optical system provided in one embodiment of the present utility model;

[0019] Figure 2 A schematic diagram of a transmission compensation component provided by an embodiment of the present utility model;

[0020] Figure 3 Another schematic diagram of a transmission compensation component provided by an embodiment of the present utility model;

[0021] Figure 4 A schematic diagram of a collecting mirror provided in one embodiment of the present utility model;

[0022] Figure 5 Another schematic diagram of a collecting mirror provided in one embodiment of the present utility model. DETAILED DESCRIPTION

[0023] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0024] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating positions or relationships, are based on the positions or relationships shown in the accompanying drawings and are intended solely to facilitate the description of this utility model and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0026] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Example 1

[0028] An embodiment of the present invention provides an optical system, referring to Figure 1 , including: a collecting mirror 1, suitable for collecting signal light generated by the incident light beam irradiating the surface of the sample 2; a detector 3; a transmission compensation component 4, located in the optical path between the collecting mirror 1 and the detector 3, the transmission compensation component 4 includes: a transmitter, used to split the signal light from the collecting mirror 1 into a transmission beam; a compensation mirror, used to compensate for the optical path difference of the transmission beam.

[0029] It should be noted that the signal light includes light beams of different wavelengths, and the optical path difference is caused by the different incident angles of the light beams in the signal light entering the transmitter, resulting in different optical paths of the signal light in the transmitter.

[0030] The technical party of the present application uses a compensation mirror to compensate the optical path difference of the transmitted beam split by the transmitter, thereby compensating for the optical path change caused by the transmitter, so that the optical path difference between each light in the transmitted beam detected by the detector is reduced, thereby improving the beam quality.

[0031] In this embodiment, for the signal light emitted from the same collecting mirror 1 in different directions, the longer the optical path of the signal light in the transmitter, the shorter the optical path of the signal light in the compensation mirror. Conversely, the shorter the optical path of the signal light in the transmitter, the longer the optical path of the signal light in the compensation mirror.

[0032] In this embodiment, the compensating mirror compensates for the optical path difference generated by the signal light in the transmitter. For example, when the standard optical path is 100 microns, if the optical path of the signal light in the transmitter is 90 microns, the optical path of the signal light in the compensating mirror is 10 microns. If the optical path of the signal light in the transmitter is 70 microns, the optical path of the signal light in the compensating mirror is 30 microns. In this way, the compensating mirror can maintain the optical path of the signal light at the standard optical path, thereby improving the beam quality of the signal light.

[0033] In this embodiment, there are multiple transmission compensation components 4, including a first transmission compensation component 41 and a second transmission compensation component 42. There are one or more detectors 3, including a first detector 3a and a second detector 3b. The optical system further includes a splitter mirror, which is used to separate the signal light from different angles collected by the collector mirror 1 and converge them onto the first detector 3a and the second detector 3b, respectively. The first transmission compensation component 41 is located in the optical path between the splitter mirror and the first detector 3a; and the second transmission compensation component 42 is located in the optical path between the splitter mirror and the second detector 3b.

[0034] In this embodiment, a part of the collecting mirror 1 is a reflecting collecting mirror 11, and the other part of the collecting mirror 1 is a focusing collecting mirror 12; the first transmission compensation component 41 is located in the optical path between the reflecting collecting mirror 11 and the first detector 3a; the second transmission compensation component 42 is located in the optical path between the focusing collecting mirror 12 and the second detector 3b.

[0035] In this embodiment, the first transmission compensation component 41 includes a first transmitter 411 and a first compensation mirror 412. The first transmitter 411 is used to split the signal light from the reflective collection mirror 11 into a transmission beam and an additional signal light. The first compensation mirror 412 is used to compensate for the optical path difference of the transmission beam emitted by the first transmitter 411, thereby reducing the optical path difference between the light rays in the transmission beam caused by the first transmitter 411.

[0036] In this embodiment, the second transmission compensation component 42 includes a second transmitter 421 and a second compensation mirror 422. The second transmitter 421 is used to split the signal light from the focusing and collecting mirror 12 into a transmission beam and an additional signal light. The second compensation mirror 422 is used to compensate for the optical path difference of the transmission beam emitted by the second transmitter 421, thereby reducing the optical path difference between the light rays in the transmission beam caused by the second transmitter 421.

[0037] In this embodiment, the detector includes a first sub-detector and a second sub-detector. Specifically, the first detector 3a includes a first sub-detector 31 and a second sub-detector 32. The second detector 3b includes a first sub-detector 33 and a second sub-detector 34.

[0038] In this embodiment, the transmitter is further configured to separate another portion of light from the transmitted split beam to form additional signal light. The first transmitter 411 is configured to separate the transmitted split beam from the additional signal light, and the second transmitter 421 is configured to separate the transmitted split beam from the additional signal light. The first sub-detector 31 detects the transmitted split beam generated by the first transmitter 411, and the second sub-detector 32 detects the additional signal light generated by the first transmitter 411. The first sub-detector 33 detects the transmitted split beam generated by the second transmitter 421, and the second sub-detector 34 detects the additional signal light generated by the second transmitter 421.

[0039] In this embodiment, the first transmission compensation component 41 and the second transmission compensation component 42 are arranged at different positions in the optical system, and can respectively compensate for the optical path difference of signal lights in different optical paths, thereby improving the beam quality.

[0040] In this embodiment, reference Figure 2 Specifically, the first transmissive device 411 and the first compensating mirror 412 have the same structure, and the second transmissive device 421 and the second compensating mirror 422 have the same structure.

[0041] The compensating mirror and the transmissive device are mirror-symmetrical about a reference plane, and the reference plane is perpendicular to the propagation direction of the light in the transmitted beam split between the transmissive device and the compensating mirror that passes through the optical axis of the collecting mirror. Specifically, the first compensating mirror 412 and the first transmissive device 411 are mirror-symmetrical about a first reference plane, and the first reference plane is perpendicular to the propagation direction of the light in the transmitted beam split between the first transmissive device 411 and the first compensating mirror 412 that passes through the optical axis of the reflecting collecting mirror 11. The second transmissive device 421 and the second compensating mirror 422 are mirror-symmetrical about a second reference plane, and the second reference plane is perpendicular to the propagation direction of the light in the transmitted beam split between the second transmissive device 421 and the second compensating mirror 422 that passes through the optical axis of the focusing collecting mirror 12.

[0042] refer to Figure 2The optical path length of signal light a in the first transmitter 411 is greater than the optical path length of signal light b in the first transmitter 411, and the optical path length of signal light a in the first compensation mirror 412 is less than the optical path length of signal light b in the first compensation mirror 412. The optical path length of signal light b in the first transmitter 411 is greater than the optical path length of signal light c in the first transmitter 411, and the optical path length of signal light b in the first compensation mirror 412 is less than the optical path length of signal light c in the first compensation mirror 412. The optical path length of signal light c in the first transmitter 411 is greater than the optical path length of signal light d in the first transmitter 411, and the optical path length of signal light c in the first compensation mirror 412 is less than the optical path length of signal light d in the first compensation mirror 412. In this way, the optical path length difference of the transmitted split beam emitted by the first transmitter 411 can be compensated by the first compensation mirror 412, thereby improving the beam quality of the transmitted split beam.

[0043] It should be noted that the same implementation in this embodiment can also be applied to the second transmissive device 421 and the second compensation mirror 422 to achieve the same technical effect.

[0044] In this embodiment, there are multiple collecting mirrors 1, and different collecting mirrors 1 are used to collect signal light from different directions on the surface of the sample 2. In other embodiments, there is only one collecting mirror 1.

[0045] In this embodiment, since the reflection angles of the signal light in different directions on the surface of the sample 2 are different, it is necessary to set a plurality of different collecting mirrors 1 at different positions in the optical system to collect the signal light at each reflection angle and avoid the loss of signal light.

[0046] In this embodiment, the optical system further includes a support platform 5. A portion of the collecting mirror 1 is a reflective collecting mirror 11, and another portion of the collecting mirror 1 is a focusing collecting mirror 12. The orthographic projection of the reflective collecting mirror 11 on the surface of the support platform 5 is located around the side of the orthographic projection of the focusing collecting mirror 12 on the surface of the support platform 5.

[0047] In this embodiment, reference Figure 4 and Figure 5 The reflection and collection mirror 11 is suitable for collecting signal light with a reflection angle greater than a preset angle. The reflection and collection mirror 11 can be a reflection cup with openings at both the bottom and the top.

[0048] In this embodiment, reference Figure 5 The focusing and collecting mirror 12 may be a convex lens, and the focusing and collecting mirror 12 is suitable for collecting signal light whose reflection angle is less than or equal to a preset angle.

[0049] In this embodiment, reference Figure 1The optical system further includes: a light source 6, wherein the light source 6 is adapted to irradiate the sample 2 with illumination light, and the sample 2 is adapted to reflect the illumination light to form the signal light; the illumination lights of different wavelengths generated by the light source 6 are combined into a beam of illumination light and irradiated to the sample 2; or, the illumination lights of different wavelengths generated by the light source 6 are irradiated to the sample 2 at different incident angles.

[0050] In this embodiment, the illumination lights generated by the different light sources are irradiated onto the sample 2 at different incident angles. For example, the illumination light generated by the light source 61 and the illumination light generated by the light source 62 are irradiated onto the sample 2 at different incident angles.

[0051] In other embodiments of the present application, illumination lights of different wavelengths generated by different light sources are combined into one beam of illumination light and irradiated to the sample, which can reduce the energy loss of the light signal during transmission, increase the signal strength, and thus improve the detection sensitivity.

[0052] Other embodiments of the present application further include: a transmission component; the illumination light generated by the same light source is split into illumination lights in different directions by the transmission component. The transmission component can specifically be a transmitter that can change the illumination direction of the illumination light, so that the illumination light generated by the same light source is split into illumination lights in different directions by the transmission component. In one embodiment, the transmission component can be used to separate light beams of different wavelengths.

[0053] In this embodiment, the signal light includes beams of different wavelengths. The transmitter is a dichroic mirror, a wavelength filter, or a dispersion prism; alternatively, the transmitter is an energy beam splitter or a polarization beam splitter. Specifically, the first transmitter 411 is a dichroic mirror, a wavelength filter, or a dispersion prism; alternatively, the first transmitter 411 is an energy beam splitter or a polarization beam splitter. The second transmitter 421 is a dichroic mirror, a wavelength filter, or a dispersion prism; alternatively, the second transmitter 421 is an energy beam splitter or a polarization beam splitter. In this embodiment, illumination light from different directions does not interfere with each other. The illumination light can be detection light.

[0054] Illumination light from different directions is used to strike the sample surface at different angles of incidence. When the illumination light is detection light, illumination light with different angles of incidence is used to detect different types of defects, thereby improving detection efficiency. The sample may be, for example, a wafer, a semi-finished semiconductor structure, or a finished semiconductor structure. Of the illumination light from different directions striking the sample surface, one direction is perpendicular to the sample surface, while the remaining directions are at non-perpendicular angles to the sample surface.

[0055] In one embodiment, the optical system further comprises: an aperture; the aperture is located in the optical path between the collecting mirror 1 and the transmission compensation component 4, and is suitable for filtering out stray light from outside the optical system.

[0056] In this embodiment, the aperture can block stray light from outside the optical system from entering the optical system. The stray light will reduce the quality of the signal light and affect the detection results. The aperture can effectively reduce the interference of stray light, improve the quality of the signal light, and improve the performance of the optical system.

[0057] The working process of the optical system specifically includes: incident illumination light onto the sample 2 placed on the support table 5 through the light source 6, and the sample 2 reflects the illumination light to form multiple signal lights with different reflection angles; the signal light with a reflection angle greater than a preset angle is collected by the reflection collection mirror 11 to the aperture for filtering processing, and then the signal light enters the first transmission compensation component 41, and the signal light is split into a transmission beam and an additional signal light by the first transmitter 411, and the optical path difference of the transmission beam split by the first transmitter 411 is compensated by the first compensation mirror 412, the transmission beam split by the first transmitter 411 is detected by the first sub-detector 31, and the additional signal light split by the first transmitter 411 is detected by the second sub-detector 32. The signal light with a reflection angle less than or equal to the preset angle is collected by the focusing collecting mirror 12. After the signal light is collected by the focusing collecting mirror 12 to the aperture for filtering, the signal light enters the second transmission compensation component 42. The optical path difference of the transmission beam split by the second transmitter 421 is compensated by the second compensation mirror 422. The transmission beam split by the second transmitter 421 is detected by the first sub-detector 33, and the reflection beam split by the second transmitter 421 is detected by the second sub-detector 34.

[0058] In this embodiment, the compensation mirror is used to compensate for the optical path difference of the transmitted beam split by the transmitter, thereby compensating for the optical path change caused by the transmitter and improving the beam quality.

[0059] Example 2

[0060] refer to Figure 3 This embodiment also provides an optical system, which differs from Embodiment 1 in that: the transmission compensation component includes a transmitter and a compensation mirror, the compensation mirror is a wedge-shaped mirror, and the thickness of the compensation mirror decreases from the side with the smallest optical path of the signal light in the transmitter 411 to the side with the largest optical path.

[0061] Exemplarily, the first transmission compensation component 41 includes a first transmitter 411 and a first compensation mirror 412. The first compensation mirror 412 is a wedge-shaped mirror, and the thickness of the first compensation mirror 412 decreases from the side where the optical path of the signal light is the smallest to the side where the optical path is the largest in the first transmitter 411. In one embodiment, the first compensation mirror 412 is a wedge-shaped mirror, which is used to separate light beams of different wavelengths.

[0062] Exemplarily, the second transmission compensation component 42 includes a second transmitter 421 and a second compensation mirror 422. The second compensation mirror 422 is a wedge-shaped mirror, and the thickness of the second compensation mirror 422 decreases from the side where the optical path of the signal light is the smallest to the side where the optical path is the largest in the second transmitter 421. In one embodiment, the second compensation mirror 422 is a wedge-shaped mirror, which is used to separate light beams of different wavelengths.

[0063] The thickness change of the compensation mirror makes the optical path of the transmitted beam passing through different areas of the compensation mirror different, thereby compensating for the optical path change caused by the transmitter.

[0064] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An optical system, characterized in that: include: a collecting mirror, adapted to collect signal light generated by the incident light beam irradiating the surface of the sample; detector; a transmission compensation component, located in the optical path between the collecting mirror and the detector, the transmission compensation component comprising: a transmissor, for transmitting the signal light from the collecting mirror into a transmission beam splitter; The compensating mirror is used to compensate the optical path difference of the transmitted beam.

2. The optical system according to claim 1, wherein: For the signal light emitted from the same collecting mirror in different directions, the longer the optical path of the signal light in the transmitter, the shorter the optical path in the compensation mirror.

3. The optical system according to claim 1 or 2, characterized in that The transmissive device and the compensating mirror have the same structure.

4. The optical system according to claim 3, wherein: The compensating mirror and the transmitter are mirror-symmetrical about a reference plane, and the reference plane is perpendicular to a propagation direction of light passing through the optical axis of the collecting mirror in the transmission beam split between the transmitter and the compensating mirror.

5. The optical system according to claim 1 or 2, characterized in that The compensation mirror is a wedge-shaped mirror, and the thickness of the compensation mirror decreases from the side where the optical path of the signal light in the transmitter is the smallest to the side where the optical path is the largest.

6. The optical system according to claim 5, characterized in that The compensating mirror is a wedge-shaped mirror, and the wedge-shaped mirror is also used to separate light beams of different wavelengths.

7. The optical system according to claim 1, wherein: There are multiple collecting mirrors, and different collecting mirrors are used to collect signal light from different directions on the surface of the sample.

8. The optical system according to claim 7, wherein: The optical system further comprises: a support table; A portion of the collecting mirrors is a reflective collecting mirror, and another portion of the collecting mirrors is a focusing collecting mirror; the orthographic projection of the reflective collecting mirror on the surface of the support platform is located around the side of the orthographic projection of the focusing collecting mirror on the surface of the support platform.

9. The optical system according to claim 1, wherein: Also includes: A light source, wherein the light source is suitable for incident illumination light on the sample, and the sample is suitable for reflecting the illumination light to form the signal light; the illumination light of different wavelengths generated by the light source is combined into a beam of illumination light and irradiated to the sample; or the illumination light of different wavelengths generated by the light source is irradiated to the sample at different incident angles.

10. The optical system according to claim 1 or 9, characterized in that The signal light includes light beams of different wavelengths, and the transmitter is a dichroic mirror, a wavelength filter or a dispersion prism; Alternatively, the transmitter is an energy beam splitter or a polarization beam splitter.

11. The optical system according to claim 1, wherein: The transmitter is further used to separate another portion of light from the transmitted beam to form additional signal light. The detector includes: a first sub-detector and a second sub-detector. The first sub-detector is used to detect the transmitted beam, and the second sub-detector is used to detect the additional signal light.

12. The optical system according to claim 1, wherein: There are multiple transmission compensation components, including a first transmission compensation component and a second transmission compensation component; there are one or more detectors, including a first detector and a second detector; The optical system further includes: a separation mirror, the separation mirror being used to separate the signal lights of different angles collected by the collecting mirror and converge them onto the first detector and the second detector respectively; The first transmission compensation component is located in the optical path between the separation mirror and the first detector; the second transmission compensation component is located in the optical path between the separation mirror and the second detector.

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