Measuring system, measuring method thereof and photoetching equipment

Abstract

The invention provides a measurement system, a measurement method thereof and photoetching equipment, relates to the technical field of semiconductors, and can realize integration of a focusing and leveling system and an alignment system, improve the overall space occupancy rate of the measurement system, avoid difficulty in selection of mounting positions, share the same coordinate system during focusing, leveling and alignment, and improve the measurement accuracy. Therefore, the calculation accuracy of focusing, leveling and alignment is improved. The measuring system comprises a light source structure and a detection structure. The light source structure comprises a light source and a first grating. In the first working mode, a light beam emitted by the light source passes through the first grating to form first diffraction light, and the first diffraction light enters the surface of a wafer on the workpiece table; the detection structure is used for receiving the first diffracted light reflected by the surface of the wafer and indicating the workpiece table to perform focusing and leveling according to the received first diffracted light. In the second working mode, the light beam emitted by the light source enters the surface of the wafer on the workpiece table; the detection structure is used for receiving the light beams reflected by the surface of the wafer and indicating the workpiece table to align according to the received light beams.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor technology, and in particular to a measurement system and a measurement method thereof, and a lithography device. Background Art

[0002] Lithography equipment needs to be equipped with horizontal and vertical measurement systems to achieve high-precision indicators. Among them, the measurement system includes a focusing and leveling system and an alignment system. The focusing and leveling system is a system that measures the vertical height and flatness of the wafer on the workpiece stage. By adjusting the position of the wafer, the error caused by wafer defocus and tilt is reduced. The alignment system locates the position of the wafer on the workpiece stage to ensure the accuracy of the working position point.

[0003] However, in the existing measurement system, the alignment system and the leveling and focusing system are two independent systems. Since the two are designed separately and complete their own measurement work separately, the overall space occupancy rate of the measurement system is low and the installation location of each functional module is difficult to select. In addition, the two independent systems will involve problems such as switching of coordinate systems, which increases the complexity of the entire process. Summary of the invention

[0004] The measurement system and its measurement method, as well as the lithography equipment provided in the present application, can realize the integration of the focusing and leveling system and the alignment system, thereby improving the overall space occupancy rate of the measurement system and avoiding the difficulty in selecting the installation position. During focusing, leveling and alignment, the same coordinate system can be shared to improve the calculation accuracy of focusing, leveling and alignment.

[0005] In a first aspect, the present application provides a measurement system, which includes a light source structure and a detection structure, wherein the light source structure includes a light source and a first grating. In a first working mode, a light beam emitted by the light source passes through the first grating to form a first diffracted light, and the first diffracted light is incident on the surface of a wafer on a work stage; the detection structure is used to receive the first diffracted light reflected by the surface of the wafer, and instruct the work stage to focus and level according to the received first diffracted light, so as to achieve focusing and leveling of the wafer on the work stage. In a second working mode, a light beam emitted by the light source is incident on the surface of the wafer on the work stage; the detection structure is used to receive the light beam reflected by the surface of the wafer, and instruct the work stage to align according to the received light beam, so as to achieve alignment of the wafer on the work stage.

[0006] In the present application, only one light source structure and one detection structure in the measurement system are needed to realize focusing and leveling of the work stage and the wafer in the first working mode, and to realize alignment of the work stage and the wafer in the second working mode. Specifically, using the same light source structure, the first diffracted light is incident on the wafer surface in the first working mode, and the light beam is incident on the wafer surface in the second working mode. Using the same detection structure, the first diffracted light reflected from the wafer surface is received in the first working mode, and the light beam reflected from the wafer surface is received in the second working mode. In addition, the detection structure can also instruct the work stage to focus and level according to the received first diffracted light, and instruct the work stage to align according to the received light beam, thereby realizing focusing, leveling and alignment of the wafer on the work stage.

[0007] The embodiment of the present application realizes the integration of the focusing and leveling system and the alignment system by multiplexing the optical path when focusing and leveling the workpiece stage and aligning the workpiece stage, and the focusing and leveling system and the alignment system are no longer two independent structures. This improvement can improve the overall space occupancy rate of the measurement system; the light emitted by the light source structure (the first diffracted light and the light beam) is incident on the surface of the wafer, and the light reflected by the surface of the wafer (the first diffracted light and the light beam) can be incident on the detection structure, and the installation position selection is not difficult due to the overlap of the installation positions of some functional modules of the focusing and leveling system and some working modules of the alignment system. In addition, when focusing, leveling and aligning the same irradiation position, the position of the same light source structure and the same detection structure relative to the wafer remains unchanged. When focusing, leveling and aligning, the same coordinate system can be shared to improve the calculation accuracy of focusing, leveling and alignment, and avoid the position of the independent focusing and leveling system relative to the wafer, and the position of the alignment system relative to the wafer 41. There is a deviation, resulting in a reduction in the calculation accuracy of focusing, leveling and alignment.

[0008] In some possible implementations, in order to make the light source structure emit the first diffracted light in the first working mode and emit the light beam in the second working mode, it can be achieved by the following two methods:

[0009] In a first possible implementation, the light source includes a first light source, the light source structure further includes a first push-pull structure, and the detection structure includes a first photodetector, wherein the first photodetector may be a camera.

[0010] In the first working mode, the first push-pull structure is used to move the first grating to the light-emitting side of the first light source, so that the light beam emitted by the first light source is first incident on the first grating. The first grating includes a plurality of diffraction strips that are light and dark. Therefore, the illumination light incident on the first grating is converted into the first diffraction light after passing through the first grating, and is incident on the surface of the wafer on the worktable. Since the reflection ability at each position on the wafer surface is the same (or substantially the same), the first diffraction light is still incident on the first photodetector in the form of diffraction light after being reflected from the irradiation position. The first photodetector instructs the worktable to focus and level according to the received first diffraction light, so as to achieve focusing and leveling of the wafer set on the worktable.

[0011] In the second working mode, the first push-pull structure is used to move the first grating out of the light-emitting side of the first light source, so that the light beam emitted by the first light source can be directly incident on the surface of the wafer on the workpiece stage. Since the reflection ability at each position on the wafer surface is the same (or substantially the same), the light beam is still incident on the first photodetector in the form of illumination light after being reflected at the irradiation position. The first photodetector instructs the workpiece stage to align according to the received light beam, so as to align the wafer set on the workpiece stage.

[0012] In the second possible implementation,

[0013] The light source includes a first light source and a second light source, and the first grating is located at the light-emitting side of the first light source. On this basis, the light source structure can also include the above-mentioned projection lens and the first prism, and the detection structure can also include an imaging lens and a second prism.

[0014] In the first working mode, the first grating is fixed on the light-emitting side of the first light source, so that the light beam emitted by the first light source is first incident on the first grating. The first grating includes a plurality of diffraction strips that are light and dark. Therefore, the illumination light incident on the first grating is converted into the first diffraction light after passing through the first grating, and is incident on the irradiation position of the wafer surface. Since the reflection ability at each position on the wafer surface is the same (or substantially the same), the first diffraction light is still incident on the first photodetector in the form of diffraction light after being reflected from the irradiation position on the wafer surface. The first photodetector instructs the work stage to focus and level according to the received first diffraction light, so as to achieve focusing and leveling of the wafer set on the work stage.

[0015] In the second working mode, the second light source emits a light beam instead of the first light source. The light beam emitted by the second light source is directly incident on the irradiation position on the wafer surface. Since the reflection capability at each position on the wafer surface is the same (or substantially the same), after the light beam is reflected from the irradiation position, it is still incident on the first photodetector in the form of illumination light. The first photodetector instructs the work stage to align according to the received light beam, so as to align the wafer set on the work stage.

[0016] In some possible implementations, the light source structure further includes a first semi-transparent and semi-reflective mirror. The first semi-transparent and semi-reflective mirror is used to transmit the first diffracted light emitted by the first grating in the first working mode, and to reflect the light beam emitted by the second light source in the second working mode, so that the first diffracted light and the light beam are incident on the wafer surface of the workpiece stage along the same optical path.

[0017] In some possible implementations, the detection structure includes a first photodetector, a second grating, and a second push-pull structure to further improve the accuracy of the first operating mode, which is described in detail below in conjunction with specific circumstances.

[0018] The first diffracted light is reflected by the irradiation position of the work stage and then emitted in the form of diffracted light. The second push-pull structure moves the second grating to the light incident side of the first photodetector. The first diffracted light reflected by the work stage is first incident on the second grating. The second grating includes a plurality of diffraction strips that are light and dark. Therefore, the first diffracted light incident on the second grating is converted into the second diffracted light after passing through the second grating. The first photodetector receives the second diffracted light emitted by the second grating and instructs the work stage to focus and level according to the received first diffracted light.

[0019] After the first diffracted light is incident on the second grating, the moiré fringes of light and dark in the emitted second diffracted light are further refined, so the number of moiré fringes of light and dark in the second diffracted light is greater than the number of moiré fringes of light and dark in the first diffracted light. Therefore, compared with the first diffracted light, the error of the focus offset or leveling offset determined by the first photodetector based on the second diffracted light is more accurate.

[0020] In the second working mode, after the light beam is reflected by the irradiation position on the wafer surface, it is incident on the first photodetector, and the first photodetector instructs the worktable to align according to the received light beam, so as to align the wafer set on the worktable. Among them, since the second push-pull structure moves the second grating out of the light incident side of the first photodetector, the light beam reflected by the irradiation position on the wafer surface is directly incident on the first photodetector.

[0021] In another possible implementation, the detection structure includes a first photodetector, a second photodetector, and a second grating.

[0022] In the first working mode, the second grating is fixed on the light incident side of the first photodetector. The first diffraction light is reflected by the irradiation position of the workpiece stage and then incident on the second grating. The second grating includes a plurality of diffraction strips alternating between light and dark. Therefore, the first diffraction light incident on the second grating is converted into second diffraction light after passing through the second grating. The first photodetector receives the second diffraction light emitted by the second grating and instructs the workpiece stage to focus and level according to the received first diffraction light.

[0023] In the second working mode, the light beam is reflected by the irradiation position on the wafer surface and then directly incident on the second photodetector. The second photodetector instructs the workpiece stage to align according to the received light beam.

[0024] In some possible implementations, the detection structure may further include a second semi-transparent and semi-reflective mirror, and the second semi-transparent and semi-reflective mirror is located on the light incident side of the second grating and the second photodetector.

[0025] In the first working mode, the second semi-transparent and semi-reflective mirror is used to transmit the first diffraction light reflected from the irradiated position on the wafer surface to the second grating; in the second working mode, the second semi-transparent and semi-reflective mirror is used to reflect the light beam reflected from the irradiated position on the wafer surface to the second photodetector, so that the first diffraction light and the light beam emitted with the same optical path after being reflected from the irradiated position on the wafer surface are respectively incident on the second grating and the second photodetector.

[0026] In some possible implementations, in a first working mode, the detection structure generates a first indication signal according to the first diffracted light, and sends the first indication signal to the work stage; the work stage performs focusing and leveling according to the first indication signal to achieve focusing of the wafer disposed on the work stage. In a second working mode, the detection structure generates a second indication signal according to the light beam, and sends the second indication signal to the work stage; the work stage performs alignment according to the second indication signal to achieve alignment of the wafer disposed on the work stage.

[0027] In some possible implementations, in addition to realizing the alignment function, the second working mode can also perform rough alignment on the workpiece stage before focusing and leveling. The purpose of rough alignment is to correct the distance difference between the irradiation position on the wafer surface and the preset detection position in the horizontal direction during focusing and leveling within a reasonable error range to avoid the irradiation position being too far from the preset detection position, resulting in focusing and leveling at the wrong irradiation position. The difference between rough alignment and alignment is that the requirements for the distance difference between the irradiation position and the preset detection position in the horizontal direction are different.

[0028] In some possible implementations, in addition to realizing the focusing and leveling functions, the first operating mode can also adjust the focal length between the irradiation position on the wafer surface and the detection structure before alignment, so that during alignment, the detection structure can be used to capture a clearer first image, thereby improving alignment accuracy.

[0029] In a second aspect, the present application provides a lithography device, including an exposure light source, a mask stage, a lens system, a workpiece stage, and the measurement system of the first aspect, wherein the workpiece stage is used to carry a wafer. The lens system is disposed between the light source structure and the detection structure, and the lens system is disposed opposite to a preset detection position in the wafer for focusing, leveling, and alignment. When the wafer is photolithographically processed, the light emitted by the exposure light source is projected onto the mask to form a light projection pattern; the lens system receives the light projection pattern and projects the light projection pattern onto the wafer.

[0030] After the workpiece stage is calibrated by the measurement system, the position and flatness of the irradiation position on the wafer surface and the preset detection position in the horizontal direction can be within the range required by the user; the error between the irradiation position on the wafer surface and the focal length of the lens system 30, and the error between the preset detection position on the wafer surface and the focal length of the lens system 30 can be within the range required by the user. Based on this, in some possible implementation methods, the lens system 30 of the embodiment of the present application can be arranged between the light source structure and the detection structure, and arranged directly opposite to the preset detection position on the wafer surface for focusing, leveling and alignment. In this way, taking the exposure process as an example, the light used for exposure can be accurately projected on the irradiation position through the lens system, thereby improving the process accuracy.

[0031] In a third aspect, the present application provides a correction method for a lithography device, the correction method comprising: the light source structure further comprises a first push-pull structure, and the light source comprises a first light source. The light source is used to emit a light beam, and the light beam passes through a first grating to form a first diffracted light, comprising: using the first push-pull structure to move the first grating to the light-emitting side of the first light source; using the first light source to emit a light beam, and the light beam passes through the first grating to form the first diffracted light. The light source is used to emit a light beam, and the light beam is incident on the wafer surface of the worktable, comprising: using the first push-pull structure to move the first grating out of the light-emitting side of the first light source; using the first light source to emit a light beam, and the light beam is incident on the wafer surface on the worktable.

[0032] In some possible implementations, the light source includes a first light source and a second light source, and the first grating is located at the light-emitting side of the first light source. Using the light source to emit a light beam, the light beam passes through the first grating to form a first diffracted light, including: using the first light source to emit a light beam, the light beam passes through the first grating to form the first diffracted light. Using the light source to emit a light beam, the light beam is incident on the wafer surface of the workpiece stage, including: using the second light source to emit a light beam, the light beam is incident on the wafer surface of the workpiece stage.

[0033] In some possible implementations, the light source structure further includes a first semi-transparent and semi-reflective mirror. The first semi-transparent and semi-reflective mirror is used to transmit the first diffracted light emitted by the first grating, and the first semi-transparent and semi-reflective mirror is used to reflect the light beam emitted by the second light source, so that the first diffracted light and the light beam are incident on the workpiece stage along the same optical path.

[0034] In some possible implementations, the detection structure includes a first photodetector. The detection structure is used to receive the first diffracted light reflected from the surface of the wafer, and the work stage is instructed to focus and level according to the received first diffracted light, including: the first photodetector is used to receive the first diffracted light reflected from the surface of the wafer, and the work stage is instructed to focus and level according to the received first diffracted light. The detection structure is used to receive the light beam reflected from the surface of the wafer, and the work stage is instructed to align according to the received light beam, including: the first photodetector is used to receive the light beam reflected from the surface of the wafer, and the work stage is instructed to align according to the received light beam.

[0035] In some possible implementations, the detection structure includes a first photodetector, a second push-pull structure, and a second grating. The detection structure is used to receive the first diffracted light reflected from the surface of the wafer, and the work stage is instructed to focus and level according to the received first diffracted light, including: using the second push-pull structure to move the second grating to the light incident side of the first photodetector; using the second grating to receive the first diffracted light reflected from the surface of the wafer, and incident the second diffracted light to the first photodetector; instructing the work stage to focus and level according to the received second diffracted light through the first photodetector; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light. The detection structure is used to receive the light beam reflected from the surface of the wafer, and the work stage is instructed to align according to the received light beam, including: using the second push-pull structure to move the second grating out of the light incident side of the first photodetector; receiving the light beam reflected from the surface of the wafer through the first photodetector, and instructing the work stage to align according to the received light beam.

[0036] In some possible implementations, the detection structure includes a first photodetector, a second photodetector, and a second grating. The detection structure is used to receive the first diffracted light reflected from the surface of the wafer, and the work stage is instructed to focus and level according to the received first diffracted light, including: the first diffracted light reflected from the surface of the wafer is received by the second grating, and the second diffracted light is incident on the first photodetector; the first photodetector is used to instruct the work stage to focus and level according to the received second diffracted light; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light. The detection structure is used to receive the light beam reflected from the surface of the wafer, and the work stage is instructed to align according to the received light beam, including: the second photodetector is used to receive the light beam reflected from the surface of the wafer, and the work stage is instructed to align according to the received light beam.

[0037] In some possible implementations, the detection structure further includes a second semi-transparent and semi-reflective mirror, which transmits the first diffracted light reflected by the wafer surface to the second grating and reflects the light beam reflected by the wafer surface to the second photodetector.

[0038] In some possible implementations, the detection structure instructs the work stage to perform focusing and leveling according to the received first diffracted light, including: using the detection structure to receive the first diffracted light, and imaging the first diffracted light into a first image containing moiré fringes. Using the detection structure to obtain a focus offset according to the first image and the preset position information of the preset detection position on the wafer surface, and sending the focus offset to the work stage, and the work stage instructs the work stage to focus according to the focus offset; and using the detection structure to obtain a first distance and a first height difference between a plurality of first target detection points in the first direction of the first image, obtain a first leveling offset according to the first distance and the first height difference, and send the first leveling offset to the work stage, and the work stage instructs the work stage to level in the first direction according to the first leveling offset; and using the detection structure to obtain a second distance and a second height difference between a plurality of second target detection points in the second direction of the first image, obtain a second leveling offset according to the second distance and the second height difference, and send the second leveling offset to the work stage, and the work stage instructs the work stage to level in the second direction according to the second leveling offset; wherein, in the first image, the first direction is perpendicular to the second direction.

[0039] In some possible implementations, the light beam received by the detection structure instructs the workpiece stage to align, including: using the detection structure to receive the light beam, and imaging the light beam into a second image. The second image is image matched with a preset image of a preset detection position on the workpiece stage by the detection structure to obtain an alignment offset, and the workpiece stage is instructed to align according to the alignment offset.

[0040] In some possible implementations, a light beam is emitted by a light source, and the light beam passes through a first grating to form a first diffraction light, and the first diffraction light is incident on the surface of a wafer on a work stage; a detection structure is used to receive the first diffraction light reflected by the wafer surface, and before the work stage is instructed to focus and level according to the received first diffraction light, the correction method also includes: an light beam is emitted by a light source, and the light beam is incident on the surface of the wafer on the work stage; a detection structure is used to receive the light beam reflected by the wafer surface, and before the work stage is instructed to perform coarse alignment according to the received light beam; and / or, an light beam is emitted by a light source, and the light beam is incident on the surface of the wafer on the work stage; a detection structure is used to receive the light beam reflected by the wafer surface, and before the work stage is instructed to align according to the received light beam, the correction method also includes: an light beam is emitted by a light source, and the light beam passes through a first grating to form a first diffraction light, and the first diffraction light is incident on the surface of the wafer on the work stage; a detection structure is used to receive the first diffraction light reflected by the wafer surface, and before the focal length between the light source and the wafer surface is adjusted according to the received first diffraction light.

[0041] The third aspect and any implementation of the third aspect correspond to the first aspect and any implementation of the first aspect, respectively. The technical effects corresponding to the third aspect and any implementation of the third aspect can refer to the technical effects corresponding to the first aspect and any implementation of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0043] Figure 1 A schematic diagram of the structure of a lithography device provided in an embodiment of the present application;

[0044] Figure 2a A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0045] Figure 2b A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0046] Figure 3 A schematic diagram of moiré fringes provided in an embodiment of the present application;

[0047] Figure 4a A schematic diagram of focusing a workpiece stage provided in an embodiment of the present application;

[0048] Figure 4b A schematic diagram of leveling a workpiece table provided in an embodiment of the present application;

[0049] Figure 4c A schematic diagram of leveling a workpiece table provided in an embodiment of the present application;

[0050] Figure 4d A schematic diagram of aligning a workpiece stage provided in an embodiment of the present application;

[0051] Figure 5a A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0052] Figure 5b A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0053] Figure 6a A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0054] Figure 6bA schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0055] Figure 7 A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0056] Figure 8 A schematic diagram of a first diffracted light and a second diffracted light provided in an embodiment of the present application;

[0057] Figure 9a A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0058] Figure 9b A schematic diagram of the structure of a measurement system provided in an embodiment of the present application;

[0059] Fig.10 A flowchart of a calibration method provided in an embodiment of the present application.

[0060] Reference numerals:

[0061] 10-light source; 20-mask stage; 21-mask plate; 30-lens system; 40-workpiece stage; 41-wafer; 50-light source structure; 51-first light source; 52-first grating; 53-projection objective lens; 54-first prism; 55-second light source; 56-first semi-transparent and semi-reflective mirror; 60-detection structure; 61-first photodetector; 62-imaging objective lens; 63-second prism; 64-second grating; 65-second semi-transparent and semi-reflective mirror; 66-second photodetector. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0063] The words "first", "second" and the like mentioned herein do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "an" do not indicate quantity limitation, but indicate the existence of at least one.

[0064] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way. In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more.

[0065] like Figure 1 As shown, the embodiment of the present application provides a lithography device, which includes an exposure light source 10, a mask stage 20, a lens system 30, and a workpiece stage 40. The mask stage 20 can be used to carry a mask plate 21, and the workpiece stage 40 can be used to carry a wafer 41.

[0066] The photolithography equipment can perform photolithography on the wafer 41 to transfer the pattern on the mask 21 to the wafer 41 to form a desired circuit or structure, etc. In the present application, the photolithography process includes processes such as exposure, development, and etching.

[0067] For example, the light emitted by the exposure light source 10 is projected onto the mask plate 21 to form a light projection pattern; the lens system 30 receives the light projection pattern and projects the light projection pattern onto the wafer 41 to perform photolithography on the film layer.

[0068] Before using the photolithography equipment to perform photolithography on the wafer 41 , it is necessary to perform focusing, leveling and alignment on the wafer 41 on the workpiece stage 40 to improve the accuracy of the photolithography process.

[0069] It should be understood that when focusing, leveling and aligning the wafer 41, a certain position of the wafer 41 can be used as a preset detection position, and light is projected onto the wafer 41 and reflected by the wafer 41. In this case, focusing, leveling and aligning the workpiece stage 40 is the same as focusing, leveling and aligning the wafer 41.

[0070] In addition, those skilled in the art should know that focusing the wafer 41 means adjusting the vertical distance from the wafer 41 to the lens system 30. Leveling the wafer 41 means adjusting the flatness of the wafer 41. Aligning the wafer 41 means adjusting the horizontal position of the wafer 41 so that the irradiation position of the light projected on the wafer 41 is within the allowable error range with the preset detection position. The vertical direction is the direction in which the lens system 30 points to the wafer 41, and the horizontal direction is the direction perpendicular to the vertical direction.

[0071] For example, if the wafer 41 is out of focus or tilted relative to the lens system 30 , some areas in the exposure field of view may be outside the effective focal depth, seriously affecting the photolithography quality. Therefore, a focusing and leveling system must be used to accurately focus and level the wafer 41 .

[0072] As mentioned in the background technology, the measurement system configured in the existing lithography equipment includes a focusing and leveling system and an alignment system. The focusing and leveling system is a system for measuring the vertical height and flatness of the wafer 41. By adjusting the position of the wafer 41, the error caused by the defocus and tilt of the wafer 41 is reduced. The alignment system is to locate the position of the wafer 41 to ensure the accuracy of the working position point.

[0073] However, in the existing measurement system, the alignment system and the leveling and focusing system are two independent systems. Since the two are designed separately and complete their own measurement work separately, the overall space occupancy rate of the measurement system is low and the installation location of each functional module is difficult to select. In addition, the two independent systems will involve problems such as switching of coordinate systems, which increases the complexity of the entire process.

[0074] Based on this, the lithography equipment provided in the embodiment of the present application includes a measurement system, which can be used for focusing, leveling and alignment before the exposure process, and can also be used for focusing, leveling and alignment before the etching process.

[0075] like Figure 2a and Figure 2b As shown, the measurement system includes a light source structure 50 and a detection structure 60. The wafer 41 on the workpiece stage 40 has the function of reflecting light. The light emitted by the light source structure 50 is incident on the irradiation position of the wafer 41, and can be reflected by the irradiation position to the detection structure 60. The detection structure 60 converts the received light into an image, which is an image taken by the detection structure for the irradiation position. Among them, the dotted line with an arrow in the figure represents light.

[0076] In the present application, the measurement system integrates the focusing and leveling system and the alignment system, and realizes the focusing and leveling and alignment functions by making the measurement system work in different working modes. The light source structure 50 includes a light source and a first grating.

[0077] Specifically, based on the calculation principle of focusing and leveling, in the first working mode, the light source emits a light beam, the light beam passes through the first grating to form a first diffracted light, the first diffracted light is incident on the surface of the wafer 41 on the work stage 40, and the surface of the wafer 41 reflects the received first diffracted light to the detection structure 60. The detection structure 60 is used to instruct the work stage 40 to focus and level according to the first diffracted light, so as to achieve focusing and leveling of the wafer 41 set on the work stage 40.

[0078] Those skilled in the art should know that the first diffracted light includes moiré fringes of light and dark. The moiré fringes of light and dark can be a plurality of rectangular bright fringes arranged at intervals ( Figure 3 ), of course, the shape of the light and dark moiré fringes can also be other, and the embodiments of the present application do not limit it. For the sake of convenience, the following description is given by taking the light and dark moiré fringes as a plurality of rectangular bright fringes with intervals set as an example. In some possible implementations, the width of the moiré fringes in the first direction is adjustable, or the width of the moiré fringes in the first direction is fixed. Optionally, the measurement system may include a plurality of first gratings with different slit widths. According to actual needs, in the first working mode, the first gratings with different slit widths can be moved to the light-emitting side of the light source to achieve adjustable width of the moiré fringes in the first direction. Among them, the first direction is the direction in which any moiré fringe points to the moiré fringes adjacent to it.

[0079] For example, Figure 4a The calculation principle diagram of focusing is shown. After the first diffracted light emitted by the light source structure 50 is incident on the irradiation position on the surface of the wafer 41, it is reflected from the irradiation position to the detection structure 60, and the detection structure 60 converts the first diffracted light into a first image. Since the light incident on the detection structure 60 is the first diffracted light, the first image includes moiré fringes.

[0080] When there is a vertical distance difference between the irradiation position and the preset detection position (that is, when the wafer needs to be focused), there is a difference between the preset image corresponding to the preset detection position and the first image corresponding to the irradiation position. The vertical distance difference between the irradiation position and the preset detection position can be reflected by the moiré fringes of the preset image and the moiré fringes of the first image. Specifically, the first position of a moiré fringe in the first image and the second position of the moiré fringe in the preset image are determined, and the distance between the first position and the second position in the first direction is calculated, which is the distance ΔX1 from the actual light path reflected by the irradiation position to the preset light path reflected by the preset detection position. Among them, the first direction is the direction in which any moiré fringe points to the moiré fringe adjacent to it.

[0081] Further, the detection structure 60 is based on the formula The focus offset ΔZ1 is calculated, and a first indication signal is generated, and the first indication signal is sent to the work stage 40. After receiving the first indication signal, the work stage 40 performs vertical focusing to achieve focusing of the wafer 41 set on the work stage 40. The focus offset ΔZ1 refers to: the vertical distance difference between the irradiation position and the preset detection position. γ refers to the angle between the actual light path or the preset light path and the work stage 40. The above-mentioned second position and γ are the preset position information of the preset detection position.

[0082] Here, it should be understood that the preset light path is a preset light path based on conditions such as a preset detection position and a reflection angle of the first diffracted light, and does not actually exist.

[0083] The calculation principle of leveling can be: after the detection structure 60 converts the first diffracted light into the first image, multiple (for example, two) first target detection points are selected in the first image, and the two first target detection points are arranged along the first direction; multiple (for example, two) second target detection points are selected in the first image, and the two second target detection points are arranged along the second direction. Afterwards, according to the tangent formula, the offset angle of the first image relative to the horizontal direction in the first direction and the second direction is calculated. Among them, the embodiment of the present application does not limit the specific directions of the first direction and the second direction, as long as the first direction is perpendicular to the second direction in the first image. For example, the first direction here can be the same as the first direction in the focusing stage, both of which are the direction in which any moire fringe points to the moire fringe adjacent to it, and the second direction is the extension direction of any fringe.

[0084] Specifically, Figure 4b As shown, the first distance ΔX2 in the first direction and the first height difference ΔZ2 in the vertical direction between the two first target detection points are calculated. According to the tangent formula A first leveling offset θ of the wafer 41 in the first direction relative to the horizontal direction can be obtained, and a first indication signal is generated and sent to the worktable 40. After receiving the first indication signal, the worktable 40 performs horizontal leveling to achieve leveling of the wafer 41 set on the worktable 40.

[0085] like Figure 4c As shown, the second distance ΔY in the second direction and the second height difference ΔZ3 in the vertical direction of the two second target detection points are calculated. According to the tangent formula A second leveling offset β of the wafer 41 in the second direction relative to the horizontal direction can be obtained, and a first indication signal is generated. The first indication signal is sent to the worktable 40. After receiving the first indication signal, the worktable 40 performs horizontal leveling to achieve leveling of the wafer 41 set on the worktable 40.

[0086] In the second working mode, based on the calculation principle of alignment, the light source emits a light beam incident on the irradiation position on the surface of the wafer 41, and the detection structure 60 then receives the light beam reflected by the irradiation position on the surface of the wafer 41. The detection structure 60 is used to instruct the workpiece stage 40 to align according to the received light beam. Those skilled in the art should know that the light beam emitted by the light source refers to the light directly emitted by the light source. Compared with the diffracted light, the light beam emitted by the light source is more uniform and does not have moiré fringes alternating between light and dark. Among them, the light source and the exposure light source 10 of the aforementioned lithography equipment are two different structures that provide different light in the lithography equipment.

[0087] For example, after the light beam emitted by the light source is incident on the irradiation position on the surface of the wafer 41 , it is reflected from the irradiation position to the detection structure 60 , and the detection structure 60 converts the light beam into a second image.

[0088] like Figure 4d As shown, when the irradiation position is not aligned with the preset detection position, there is a distance difference between the irradiation position and the preset detection position in the horizontal direction, and thus there is a difference between the preset image corresponding to the preset detection position and the second image corresponding to the irradiation position. Image matching technology can be used to compare the second image with the preset image, and then obtain the alignment offset, and generate a second indication signal, and send the second indication signal to the work stage 40. After receiving the second indication signal, the work stage 40 performs horizontal alignment to achieve alignment of the wafer 41 set on the work stage 40.

[0089] Based on the above-mentioned focusing and leveling principles and alignment principles, it can be seen that only one light source structure 50 and one detection structure 60 in the measurement system are needed to realize focusing and leveling of the work stage 40 and the wafer 41 in the first working mode, and to realize alignment of the work stage 40 and the wafer 41 in the second working mode. Specifically, using the same light source structure 50, the first diffracted light is incident on the surface of the wafer 41 in the first working mode, and the light beam is incident on the surface of the wafer 41 in the second working mode. Using the same detection structure 60, the first diffracted light reflected from the surface of the wafer 41 is received in the first working mode, and the light beam reflected from the surface of the wafer 41 is received in the second working mode. In addition, the detection structure 60 can also instruct the work stage 40 to focus and level according to the received first diffracted light, and instruct the work stage 40 to align according to the received light beam, thereby realizing focusing, leveling and alignment of the wafer 41 on the work stage 40.

[0090] The embodiment of the present application realizes the integration of the focusing and leveling system and the alignment system by multiplexing the optical path when focusing and leveling the workpiece stage 40 and aligning the workpiece stage 40, and the focusing and leveling system and the alignment system are no longer two independent structures. This improvement can improve the overall space occupancy rate of the measurement system; the light (first diffracted light and light beam) emitted by the light source structure 50 is incident on the surface of the wafer 41, and the light (first diffracted light and light beam) reflected by the surface of the wafer 41 can be incident on the detection structure 60, and the difficulty in selecting the installation position will not be caused by the overlap of the installation positions of some functional modules of the focusing and leveling system and some working modules of the alignment system. Furthermore, when focusing, leveling and aligning are performed on the same irradiation position, the positions of the same light source structure 50 and the same detection structure 60 relative to the wafer 41 remain unchanged. During focusing, leveling and alignment, the same coordinate system can be shared to improve the calculation accuracy of focusing, leveling and alignment, and avoid deviations between the position of the independent focusing and leveling system relative to the wafer 41 and the position of the alignment system relative to the wafer 41, which results in reduced calculation accuracy of focusing, leveling and alignment.

[0091] After the measurement system is calibrated, the position and flatness of the irradiation position on the surface of the wafer 41 and the preset detection position in the horizontal direction can be within the range required by the user; the error between the irradiation position on the surface of the wafer 41 and the focal length of the lens system 30, and the error between the preset detection position on the surface of the wafer 41 and the focal length of the lens system 30 can be within the range required by the user. Based on this, in some possible implementation methods, the lens system 30 of the embodiment of the present application can be arranged between the light source structure 50 and the detection structure 60, and arranged directly opposite to the preset detection position on the surface of the wafer 41 for focusing, leveling and alignment. In this way, taking the exposure process as an example, the light used for exposure can be accurately projected on the irradiation position through the lens system, thereby improving the process accuracy.

[0092] In some embodiments, in order to make the light source structure 50 emit the first diffracted light in the first working mode and emit the light beam in the second working mode, it can be achieved by the following two methods:

[0093] The first way, such as Figure 5a and Figure 5b As shown, the light source includes a first light source 51, the light source structure 50 also includes a first push-pull structure, and the detection structure 60 includes a first photodetector 61. The first photodetector 61 may be a camera.

[0094] In the first working mode, such as Figure 5aAs shown, the first push-pull structure is used to move the first grating 52 to the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 is first incident on the first grating 52. The first grating 52 includes a plurality of diffraction strips that are light and dark. Therefore, the illumination light incident on the first grating 52 is converted into the first diffracted light after passing through the first grating 52, and is incident on the surface of the wafer 41 on the work stage 40. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the first diffracted light is still incident on the first photodetector 61 in the form of diffracted light after being reflected from the irradiated position. The first photodetector 61 instructs the work stage 40 to focus and level according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 set on the work stage 40.

[0095] In the second working mode, such as Figure 5b As shown, the first push-pull structure is used to move the first grating 52 out of the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 can be directly incident on the surface of the wafer 41 on the workpiece stage 40. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the light beam is still incident on the first photodetector 61 in the form of illumination light after being reflected at the irradiation position. The first photodetector 61 instructs the workpiece stage 40 to align according to the received light beam, so as to realize the alignment of the wafer 41 set on the workpiece stage 40.

[0096] In some possible implementations, the embodiments of the present application do not limit the light intensity of the light beam, which is subject to actual needs.

[0097] Among some possible implementations, Figure 5a and Figure 5b As shown, the light source structure 50 may further include a projection lens 53 and a first prism 54, and the detection structure 60 may further include an imaging lens 62 and a second prism 63. The projection lens 53 is located on the light incident side of the first prism 54, and the second prism 63 is located on the light incident side of the imaging lens 62.

[0098] In the first working mode, the projection objective lens 53 and the first prism 54 are located on the optical path between the first grating 52 and the surface of the wafer 41, and are used to receive the first diffracted light emitted by the first grating 52, and adjust the optical path of the first diffracted light so that the first diffracted light is incident on the irradiation position of the surface of the wafer 41 at a preset incident angle. The imaging objective lens 62 and the second prism 63 are located on the optical path between the surface of the wafer 41 and the first photodetector 61, and are used to receive the first diffracted light reflected from the irradiation position of the surface of the wafer 41, and the first diffracted light is incident on the first photodetector 61 at a preset angle, and the first photodetector 61 instructs the workpiece stage 40 to focus and level according to the received first diffracted light.

[0099] In the second working mode, the projection objective lens 53 and the first prism 54 are located on the optical path between the first light source 51 and the surface of the wafer 41, and are used to receive the light beam emitted by the first light source 51 and adjust the light path of the light beam so that the light beam is incident on the irradiation position of the surface of the wafer 41 at a preset incident angle. The imaging objective lens 62 and the second prism 63 are located on the optical path between the surface of the wafer 41 and the first photodetector 61, and are used to receive the light beam reflected from the irradiation position of the surface of the wafer 41, and make the light beam incident on the first photodetector 61 at a preset angle.

[0100] The second case, such as Figure 6a and Figure 6b As shown, the light source includes a first light source 51 and a second light source 55, and the first grating 52 is located at the light exit side of the first light source 51. On this basis, the light source structure 50 can also include the above-mentioned projection lens 53 and first prism 54, and the detection structure 60 can also include an imaging lens 62 and a second prism 63.

[0101] In the first working mode, such as Figure 6a As shown, the first grating 52 is fixed on the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 is first incident on the first grating 52. The first grating 52 includes a plurality of diffraction strips of light and dark, so the illumination light incident on the first grating 52 is converted into the first diffracted light after passing through the first grating 52, and is incident on the irradiation position on the surface of the wafer 41. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the first diffracted light is still incident on the first photodetector 61 in the form of diffracted light after being reflected from the irradiation position on the surface of the wafer 41. The first photodetector 61 instructs the work stage 40 to perform focusing and leveling according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 disposed on the work stage 40.

[0102] In the second working mode, such as Figure 6b As shown, the second light source 55 emits a light beam, instead of the first light source 51. The light beam emitted by the second light source 55 is directly incident on the irradiation position on the surface of the wafer 41. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), after the light beam is reflected at the irradiation position, it is still incident on the first photodetector 61 in the form of illumination light. The first photodetector 61 instructs the work stage 40 to align according to the received light beam, so as to realize the alignment of the wafer 41 set on the work stage 40.

[0103] In some possible implementations, such as Figure 6a and Figure 6b As shown, the light source structure 50 may further include a first semi-transparent and semi-reflective mirror 56 , which is located on the optical path between the first grating 52 and the second light source 55 and the projection objective lens 53 .

[0104] like Figure 6a As shown, in the first working mode, the first semi-transparent and semi-reflective mirror 56 is used to transmit the first diffracted light emitted by the first grating 52; Figure 6b As shown, in the second working mode, the first semi-transparent and semi-reflective mirror 56 is used to reflect the light beam emitted by the second light source 55, so that the first diffracted light of the first working mode and the light beam of the second working mode are incident on the projection objective lens 53 along the same optical path.

[0105] The above embodiment introduces the use of the first photodetector 61 to focus, level and align the wafer 41. In other embodiments, the detection structure 60 may also include a second grating 64 and a second push-pull structure to further improve the accuracy of the first working mode, which is described in detail below in conjunction with specific circumstances.

[0106] In the first working mode, such as Figure 7 As shown, the first diffracted light is reflected by the irradiated position on the surface of the wafer 41 and then emitted in the form of diffracted light. The second push-pull structure moves the second grating 64 to the light incident side of the first photodetector 61. The first diffracted light reflected by the irradiated position on the surface of the wafer 41 is first incident on the second grating 64. The second grating 64 includes a plurality of diffraction strips that are alternately light and dark. Therefore, the first diffracted light incident on the second grating 64 is converted into the second diffracted light after passing through the second grating 64. The first photodetector 61 receives the second diffracted light emitted by the second grating 64 and instructs the work stage 40 to perform focusing and leveling according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 disposed on the work stage 40.

[0107] like Figure 8 As shown, after the first diffracted light is incident on the second grating, the moiré fringes of light and dark in the emitted second diffracted light are further refined, so the number of moiré fringes of light and dark in the second diffracted light is greater than the number of moiré fringes of light and dark in the first diffracted light. Therefore, compared with the first diffracted light, the error of the focus offset or leveling offset determined by the first photodetector 61 according to the second diffracted light is more accurate.

[0108] Those skilled in the art should know that moiré fringes are an optical phenomenon consisting of multiple parallel light and dark fringes, and the number of moiré fringes can be the total number of all light fringes added together, or the number of moiré fringes can be the total number of all light fringes and all dark fringes added together.

[0109] In the second working mode, such as Figure 5bAs shown, after the light beam is reflected by the irradiation position on the surface of the wafer 41, it is incident on the first photodetector 61. The first photodetector 61 instructs the work stage 40 to align according to the received light beam, so as to align the wafer 41 set on the work stage 40. Among them, since the second push-pull structure moves the second grating 64 out of the light incident side of the first photodetector 61, the light beam reflected by the irradiation position on the surface of the wafer 41 is directly incident on the first photodetector 61.

[0110] In another implementation, Figure 9a and Figure 9b As shown, the detection structure 60 may include a second photodetector 66 in addition to the first photodetector 61. The second photodetector 66 may also be a camera.

[0111] In the first working mode, such as Figure 9a As shown, the second grating 64 is fixed on the light incident side of the first photodetector 61. The first diffraction light is reflected by the irradiation position of the workpiece stage 40 and then incident on the second grating 64. The second grating 64 includes a plurality of diffraction strips alternating between light and dark. Therefore, the first diffraction light incident on the second grating 64 is converted into the second diffraction light after passing through the second grating 64. The first photodetector 61 receives the second diffraction light emitted by the second grating 64 and instructs the workpiece stage 40 to focus and level according to the received first diffraction light.

[0112] In the second working mode, such as Figure 9b As shown, after being reflected by the irradiation position on the surface of the wafer 41 , the light beam is directly incident on the second photodetector 66 , and the second photodetector 66 instructs the workpiece stage 40 to align according to the received light beam.

[0113] Among some possible implementations, Figure 9a and Figure 9b As shown, the detection structure 60 may further include a second semi-transparent and semi-reflective mirror 65 , which is located at the light incident side of the second grating 64 and the second photodetector 66 .

[0114] like Figure 9a As shown, in the first working mode, the second semi-transparent and semi-reflective mirror 65 is used to transmit the first diffracted light reflected by the irradiation position on the surface of the wafer 41 to the second grating 64; Figure 9b As shown, in the second working mode, the second semi-transparent and semi-reflective mirror 65 is used to reflect the light beam reflected from the irradiated position on the surface of the wafer 41 to the second photodetector 66, so that the first diffraction light and the light beam emitted with the same optical path after being reflected from the irradiated position on the surface of the wafer 41 are respectively incident on the second grating 64 and the second photodetector 66.

[0115] In some embodiments, in addition to realizing the alignment function, the second working mode can also perform rough alignment on the workpiece stage 40 before focusing and leveling. The purpose of rough alignment is to correct the distance difference between the irradiation position on the surface of the wafer 41 and the preset detection position in the horizontal direction during focusing and leveling within a reasonable error range to avoid the irradiation position being too far from the preset detection position, resulting in focusing and leveling of the wrong irradiation position. The difference between rough alignment and alignment is that the requirements for the distance difference between the irradiation position and the preset detection position in the horizontal direction are different. In addition, the principle of rough alignment is the same as that of any of the aforementioned alignments, which will not be repeated here.

[0116] In some possible implementations, in addition to realizing the focusing and leveling functions, the first working mode can also adjust the focal length between the irradiation position on the surface of the wafer 41 and the detection structure 60 before alignment, so that during alignment, a clearer first image can be taken using the detection structure 60 to improve the alignment accuracy. The principle of adjusting the focal length between the irradiation position on the surface of the wafer 41 and the detection structure 60 is the same as the principle of focusing and leveling the lens system 30 and the surface of the wafer 41 in any of the aforementioned methods, and will not be repeated here.

[0117] In another embodiment, the present application also provides a measurement method of a measurement system, wherein the measurement system includes a light source structure 50 and a detection structure 60, wherein the light source structure 50 includes a light source and a first grating 52. Fig.10 As shown, this can be achieved as follows:

[0118] S110, a light source is used to emit a light beam, and the light beam is incident on the surface of the wafer 41 of the workpiece stage 40; a detection structure 60 is used to receive the light beam reflected by the surface of the wafer 41, and the workpiece stage 40 is instructed to perform a rough alignment according to the received light beam, so as to achieve a rough alignment of the wafer 41 set on the workpiece stage 40.

[0119] By correcting the distance difference between the irradiation position and the preset detection position in the horizontal direction during focusing and leveling within a reasonable error range before focusing and leveling, it is possible to avoid the irradiation position being too far from the preset detection position, which may lead to focusing and leveling at the wrong irradiation position. The difference between coarse alignment and alignment is that the requirements for the distance difference between the irradiation position and the preset detection position in the horizontal direction are different. In addition, the principle of coarse alignment is the same as that of any of the aforementioned alignments, which will not be repeated here.

[0120] S120, a light source is used to emit a light beam, which passes through a first grating 52 to form a first diffraction light, and the first diffraction light is incident on the surface of the wafer 41 on the workpiece stage 40; a detection structure 60 is used to receive the first diffraction light reflected by the surface of the wafer 41, and the workpiece stage 40 is instructed to perform focusing and leveling according to the received first diffraction light, so as to achieve focusing and leveling of the wafer 41 set on the workpiece stage 40.

[0121] For example, Figure 4a The calculation principle diagram of focusing is shown. After the first diffracted light emitted by the light source structure 50 is incident on the irradiation position on the surface of the wafer 41, it is reflected from the irradiation position to the detection structure 60, and the detection structure 60 converts the first diffracted light into a first image. Since the light incident on the detection structure 60 is the first diffracted light, the first image includes moiré fringes.

[0122] When there is a vertical distance difference between the irradiation position and the preset detection position (that is, when the wafer needs to be focused), there is a difference between the preset image corresponding to the preset detection position and the first image corresponding to the irradiation position. The vertical distance difference between the irradiation position and the preset detection position can be reflected by the moiré fringes of the preset image and the moiré fringes of the first image. Specifically, the first position of a moiré fringe in the first image and the second position of the moiré fringe in the preset image are determined, and the distance between the first position and the second position in the first direction is calculated, which is the distance ΔX1 from the actual light path reflected by the irradiation position to the preset light path reflected by the preset detection position. Among them, the first direction is the direction in which any moiré fringe points to the moiré fringe adjacent to it.

[0123] Further, the detection structure 60 is based on the formula The focus offset ΔZ1 is calculated, and a first indication signal is generated, and the first indication signal is sent to the work stage 40. After receiving the first indication signal, the work stage 40 performs vertical focusing to achieve focusing of the wafer 41 set on the work stage 40. The focus offset ΔZ1 refers to: the vertical distance difference between the irradiation position and the preset detection position. γ refers to the angle between the actual light path or the preset light path and the work stage 40. The above-mentioned second position and γ are the preset position information of the preset detection position.

[0124] Here, it should be understood that the preset light path is a preset light path based on conditions such as a preset detection position and a reflection angle of the first diffracted light, and does not actually exist.

[0125] The calculation principle of leveling can be: after the detection structure 60 converts the first diffracted light into the first image, multiple (for example, two) first target detection points are selected in the first image, and the two first target detection points are arranged along the first direction; multiple (for example, two) second target detection points are selected in the first image, and the two second target detection points are arranged along the second direction. Afterwards, according to the tangent formula, the offset angle of the first image relative to the horizontal direction in the first direction and the second direction is calculated. Among them, the embodiment of the present application does not limit the specific directions of the first direction and the second direction, as long as the first direction is perpendicular to the second direction in the first image. For example, the first direction here can be the same as the first direction in the focusing stage, both of which are the direction in which any moire fringe points to the moire fringe adjacent to it, and the second direction is the extension direction of any fringe.

[0126] Specifically, Figure 4b As shown, the first distance ΔX2 in the first direction and the first height difference ΔZ2 in the vertical direction between the two first target detection points are calculated. According to the tangent formula A first leveling offset θ of the wafer 41 in the first direction relative to the horizontal direction can be obtained, and a first indication signal is generated and sent to the worktable 40. After receiving the first indication signal, the worktable 40 performs horizontal leveling to achieve leveling of the wafer 41 set on the worktable 40.

[0127] like Figure 4c As shown, the second distance ΔY in the second direction and the second height difference ΔZ3 in the vertical direction of the two second target detection points are calculated. According to the tangent formula A second leveling offset β of the wafer 41 in the second direction relative to the horizontal direction can be obtained, and a first indication signal is generated. The first indication signal is sent to the worktable 40. After receiving the first indication signal, the worktable 40 performs horizontal leveling to achieve leveling of the wafer 41 set on the worktable 40.

[0128] S130, a light source is used to emit a light beam, which passes through a first grating 52 to form a first diffraction light, and the first diffraction light is incident on the surface of a wafer 41 on a workpiece stage 40; a detection structure 60 is used to receive the first diffraction light reflected by the surface of the wafer 41, and the focal length between the detection structure 60 and the surface of the wafer 41 is adjusted according to the first diffraction light, so as to adjust the focal length between the detection structure 60 and the surface of the wafer 41.

[0129] By adjusting the focal length between the detection structure 60 and the work stage 40 according to the first diffracted light before alignment, a clearer first image can be taken using the detection structure 60 during alignment, thereby improving the alignment accuracy. The principle of adjusting the focal length between the irradiation position of the work stage 40 and the detection structure 60 is the same as the principle of focusing and leveling the lens system 30 and the work stage 40 in step S120, and will not be repeated here.

[0130] In some other possible implementations, after step S120, step S130 may be skipped and step S140 may be directly executed.

[0131] S140, a light source is used to emit a light beam, and the light beam is incident on the surface of the wafer 41 of the workpiece stage 40; a detection structure 60 is used to receive the light beam reflected by the surface of the wafer 41, and the workpiece stage 40 is instructed to align according to the received light beam, so as to align the wafer 41 set on the workpiece stage 40.

[0132] For example, after the light beam emitted by the light source is incident on the irradiation position on the surface of the wafer 41 , it is reflected from the irradiation position to the detection structure 60 , and the detection structure 60 converts the light beam into a second image.

[0133] like Figure 4d As shown, when the irradiation position is not aligned with the preset detection position, there is a distance difference between the irradiation position and the preset detection position in the horizontal direction, and thus there is a difference between the preset image corresponding to the preset detection position and the second image corresponding to the irradiation position. Image matching technology can be used to compare the second image with the preset image, and then obtain the alignment offset, and generate a second indication signal, and send the second indication signal to the work stage 40. After receiving the second indication signal, the work stage 40 performs horizontal alignment to achieve alignment of the wafer 41 set on the work stage 40.

[0134] Based on the above-mentioned focusing and leveling principles and alignment principles, it can be seen that only one light source structure 50 and one detection structure 60 in the measurement system are needed to realize focusing and leveling of the work stage 40 and the wafer 41 in the first working mode, and to realize alignment of the work stage 40 and the wafer 41 in the second working mode. Specifically, using the same light source structure 50, the first diffracted light is incident on the surface of the wafer 41 in the first working mode, and the light beam is incident on the surface of the wafer 41 in the second working mode. Using the same detection structure 60, the first diffracted light reflected from the surface of the wafer 41 is received in the first working mode, and the light beam reflected from the surface of the wafer 41 is received in the second working mode. In addition, the detection structure 60 can also instruct the work stage 40 to focus and level according to the received first diffracted light, and instruct the work stage 40 to align according to the received light beam, thereby realizing focusing, leveling and alignment of the wafer 41 on the work stage 40.

[0135] The embodiment of the present application realizes the integration of the focusing and leveling system and the alignment system by multiplexing the optical path when focusing and leveling the workpiece stage 40 and aligning the workpiece stage 40, and the focusing and leveling system and the alignment system are no longer two independent structures. This improvement can improve the overall space occupancy rate of the measurement system; the light (first diffracted light and light beam) emitted by the light source structure 50 is incident on the surface of the wafer 41, and the light (first diffracted light and light beam) reflected by the surface of the wafer 41 can be incident on the detection structure 60, and the difficulty in selecting the installation position will not be caused by the overlap of the installation positions of some functional modules of the focusing and leveling system and some working modules of the alignment system. Furthermore, when focusing, leveling and aligning are performed on the same irradiation position, the positions of the same light source structure 50 and the same detection structure 60 relative to the wafer 41 remain unchanged. During focusing, leveling and alignment, the same coordinate system can be shared to improve the calculation accuracy of focusing, leveling and alignment, and avoid deviations between the position of the independent focusing and leveling system relative to the wafer 41 and the position of the alignment system relative to the wafer 41, which results in reduced calculation accuracy of focusing, leveling and alignment.

[0136] In some embodiments, in order to make the light source structure 50 emit the first diffracted light in the first working mode and emit the light beam in the second working mode, it can be achieved by the following two methods:

[0137] The first way, such as Figure 5a and Figure 5b As shown, the light source includes a first light source 51, the light source structure 50 also includes a first push-pull structure, and the detection structure 60 includes a first photodetector 61. The first photodetector 61 may be a camera.

[0138] In the first working mode, such as Figure 5a As shown, the first push-pull structure is used to move the first grating 52 to the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 is first incident on the first grating 52. The first grating 52 includes a plurality of diffraction strips that are light and dark. Therefore, the illumination light incident on the first grating 52 is converted into the first diffracted light after passing through the first grating 52, and is incident on the surface of the wafer 41 on the work stage 40. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the first diffracted light is still incident on the first photodetector 61 in the form of diffracted light after being reflected from the irradiated position. The first photodetector 61 instructs the work stage 40 to focus and level according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 set on the work stage 40.

[0139] In the second working mode, such as Figure 5bAs shown, the first push-pull structure is used to move the first grating 52 out of the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 can be directly incident on the surface of the wafer 41 on the workpiece stage 40. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the light beam is still incident on the first photodetector 61 in the form of illumination light after being reflected at the irradiation position. The first photodetector 61 instructs the workpiece stage 40 to align according to the received light beam, so as to realize the alignment of the wafer 41 set on the workpiece stage 40.

[0140] In some possible implementations, the embodiments of the present application do not limit the light intensity of the light beam, which is subject to actual needs.

[0141] In some possible implementations, such as Figure 5a and Figure 5b As shown, the light source structure 50 may further include a projection lens 53 and a first prism 54, and the detection structure 60 may further include an imaging lens 62 and a second prism 63. The projection lens 53 is located on the light incident side of the first prism 54, and the second prism 63 is located on the light incident side of the imaging lens 62.

[0142] In the first working mode, the projection objective lens 53 and the first prism 54 are located on the optical path between the first grating 52 and the surface of the wafer 41, and are used to receive the first diffracted light emitted by the first grating 52, and adjust the optical path of the first diffracted light so that the first diffracted light is incident on the irradiation position of the surface of the wafer 41 at a preset incident angle. The imaging objective lens 62 and the second prism 63 are located on the optical path between the surface of the wafer 41 and the first photodetector 61, and are used to receive the first diffracted light reflected from the irradiation position of the surface of the wafer 41, and the first diffracted light is incident on the first photodetector 61 at a preset angle, and the first photodetector 61 instructs the workpiece stage 40 to focus and level according to the received first diffracted light.

[0143] In the second working mode, the projection objective lens 53 and the first prism 54 are located on the optical path between the first light source 51 and the surface of the wafer 41, and are used to receive the light beam emitted by the first light source 51 and adjust the light path of the light beam so that the light beam is incident on the irradiation position of the surface of the wafer 41 at a preset incident angle. The imaging objective lens 62 and the second prism 63 are located on the optical path between the surface of the wafer 41 and the first photodetector 61, and are used to receive the light beam reflected from the irradiation position of the surface of the wafer 41, and make the light beam incident on the first photodetector 61 at a preset angle.

[0144] The second case, such as Figure 6a and Figure 6bAs shown, the light source includes a first light source 51 and a second light source 55, and the first grating 52 is located at the light exit side of the first light source 51. On this basis, the light source structure 50 can also include the above-mentioned projection lens 53 and first prism 54, and the detection structure 60 can also include an imaging lens 62 and a second prism 63.

[0145] In the first working mode, such as Figure 6a As shown, the first grating 52 is fixed on the light-emitting side of the first light source 51, so that the light beam emitted by the first light source 51 is first incident on the first grating 52. The first grating 52 includes a plurality of diffraction strips of light and dark, so the illumination light incident on the first grating 52 is converted into the first diffracted light after passing through the first grating 52, and is incident on the irradiation position on the surface of the wafer 41. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), the first diffracted light is still incident on the first photodetector 61 in the form of diffracted light after being reflected from the irradiation position on the surface of the wafer 41. The first photodetector 61 instructs the work stage 40 to perform focusing and leveling according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 disposed on the work stage 40.

[0146] In the second working mode, such as Figure 6b As shown, the second light source 55 emits a light beam, instead of the first light source 51. The light beam emitted by the second light source 55 is directly incident on the irradiation position on the surface of the wafer 41. Since the reflection ability at each position on the surface of the wafer 41 is the same (or substantially the same), after the light beam is reflected at the irradiation position, it is still incident on the first photodetector 61 in the form of illumination light. The first photodetector 61 instructs the work stage 40 to align according to the received light beam, so as to realize the alignment of the wafer 41 set on the work stage 40.

[0147] Among some possible implementations, Figure 6a and Figure 6b As shown, the light source structure 50 may further include a first semi-transparent and semi-reflective mirror 56 , which is located on the optical path between the first grating 52 and the second light source 55 and the projection objective lens 53 .

[0148] like Figure 6a As shown, in the first working mode, the first semi-transparent and semi-reflective mirror 56 is used to transmit the first diffracted light emitted by the first grating 52; Figure 6b As shown, in the second working mode, the first semi-transparent and semi-reflective mirror 56 is used to reflect the light beam emitted by the second light source 55, so that the first diffracted light of the first working mode and the light beam of the second working mode are incident on the projection objective lens 53 along the same optical path.

[0149] The above embodiment introduces the use of the first photodetector 61 to focus, level and align the wafer 41. In other embodiments, the detection structure 60 may also include a second grating 64 and a second push-pull structure to further improve the accuracy of the first working mode, which is described in detail below in conjunction with specific circumstances.

[0150] In the first working mode, such as Figure 7 As shown, the first diffracted light is reflected by the irradiated position on the surface of the wafer 41 and then emitted in the form of diffracted light. The second push-pull structure moves the second grating 64 to the light incident side of the first photodetector 61. The first diffracted light reflected by the irradiated position on the surface of the wafer 41 is first incident on the second grating 64. The second grating 64 includes a plurality of diffraction strips that are alternately light and dark. Therefore, the first diffracted light incident on the second grating 64 is converted into the second diffracted light after passing through the second grating 64. The first photodetector 61 receives the second diffracted light emitted by the second grating 64 and instructs the work stage 40 to perform focusing and leveling according to the received first diffracted light, so as to achieve focusing and leveling of the wafer 41 disposed on the work stage 40.

[0151] like Figure 8 As shown, after the first diffracted light is incident on the second grating, the moiré fringes of light and dark in the emitted second diffracted light are further refined, so the number of moiré fringes of light and dark in the second diffracted light is greater than the number of moiré fringes of light and dark in the first diffracted light. Therefore, compared with the first diffracted light, the error of the focus offset or leveling offset determined by the first photodetector 61 according to the second diffracted light is more accurate.

[0152] Those skilled in the art should know that moiré fringes are an optical phenomenon consisting of multiple parallel light and dark fringes, and the number of moiré fringes can be the total number of all light fringes added together, or the number of moiré fringes can be the total number of all light fringes and all dark fringes added together.

[0153] In the second working mode, such as Figure 5b As shown, after the light beam is reflected by the irradiation position on the surface of the wafer 41, it is incident on the first photodetector 61. The first photodetector 61 instructs the work stage 40 to align according to the received light beam, so as to align the wafer 41 set on the work stage 40. Among them, since the second push-pull structure moves the second grating 64 out of the light incident side of the first photodetector 61, the light beam reflected by the irradiation position on the surface of the wafer 41 is directly incident on the first photodetector 61.

[0154] In another implementation, Figure 9a and Figure 9b As shown, the detection structure 60 may include a second photodetector 66 in addition to the first photodetector 61 .

[0155] In the first working mode, such as Figure 9a As shown, the second grating 64 is fixed on the light incident side of the first photodetector 61. The first diffraction light is reflected by the irradiation position of the workpiece stage 40 and then incident on the second grating 64. The second grating 64 includes a plurality of diffraction strips alternating between light and dark. Therefore, the first diffraction light incident on the second grating 64 is converted into the second diffraction light after passing through the second grating 64. The first photodetector 61 receives the second diffraction light emitted by the second grating 64 and instructs the workpiece stage 40 to focus and level according to the received first diffraction light.

[0156] In the second working mode, such as Figure 9b As shown, after being reflected by the irradiation position on the surface of the wafer 41 , the light beam is directly incident on the second photodetector 66 , and the second photodetector 66 instructs the workpiece stage 40 to align according to the received light beam.

[0157] Among some possible implementations, Figure 9a and Figure 9b As shown, the detection structure 60 may further include a second semi-transparent and semi-reflective mirror 65 , which is located at the light incident side of the second grating 64 and the second photodetector 66 .

[0158] like Figure 9a As shown, in the first working mode, the second semi-transparent and semi-reflective mirror 65 is used to transmit the first diffracted light reflected by the irradiation position on the surface of the wafer 41 to the second grating 64; Figure 9b As shown, in the second working mode, the second semi-transparent and semi-reflective mirror 65 is used to reflect the light beam reflected from the irradiated position on the surface of the wafer 41 to the second photodetector 66, so that the first diffraction light and the light beam emitted with the same optical path after being reflected from the irradiated position on the surface of the wafer 41 are respectively incident on the second grating 64 and the second photodetector 66.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A measurement system, characterized in that: include: A light source structure and a detection structure, wherein the light source structure comprises a light source and a first grating; In the first working mode, the light beam emitted by the light source passes through the first grating to form a first diffracted light, and the first diffracted light is incident on the surface of the wafer on the workpiece stage; The detection structure is used to receive the first diffracted light reflected by the surface of the wafer, and instruct the workpiece stage to perform focusing and leveling according to the received first diffracted light; In the second working mode, the light beam emitted by the light source is incident on the surface of the wafer on the workpiece stage; The detection structure is used to receive the light beam reflected by the wafer surface and instruct the workpiece stage to align according to the received light beam.

2. The measuring system according to claim 1, characterized in that The light source structure further includes a first push-pull structure, and the light source includes a first light source; In the first working mode, the first push-pull structure is used to move the first grating to the light-emitting side of the first light source, and the light beam emitted by the first light source passes through the first grating to form the first diffracted light; In the second working mode, the first push-pull structure is used to move the first grating out of the light-emitting side of the first light source, and the light beam emitted by the first light source is incident on the surface of the wafer on the workpiece stage.

3. The measuring system according to claim 1, characterized in that The light source comprises a first light source and a second light source, and the first grating is located at a light-emitting side of the first light source; In the first working mode, the light beam emitted by the first light source passes through the first grating to form the first diffracted light; In the second working mode, the light beam emitted by the second light source is incident on the surface of the wafer on the workpiece stage.

4. The measuring system according to claim 3, characterized in that The light source structure also includes a first semi-transparent and semi-reflective mirror; The first semi-transparent and semi-reflective mirror is used to: transmit the first diffracted light emitted by the first grating in the first working mode; and reflect the light beam emitted by the second light source in the second working mode, so as to make the first diffracted light and the light beam incident on the wafer surface of the worktable along the same optical path.

5. The measuring system according to any one of claims 1 to 4, characterized in that: The detection structure includes a first photodetector; In the first working mode, the first photodetector is used to receive the first diffracted light reflected by the surface of the wafer, and instruct the workpiece stage to perform focusing and leveling according to the received first diffracted light; In the second working mode, the first photodetector is used to receive the light beam reflected by the wafer surface, and instruct the workpiece stage to align according to the received light beam.

6. The measuring system according to any one of claims 1 to 4, characterized in that: The detection structure includes a first photodetector, a second push-pull structure, and a second grating; In the first working mode, the second push-pull structure is used to move the second grating to the light incident side of the first photodetector; the second grating receives the first diffracted light reflected by the wafer surface, and incidents the second diffracted light onto the first photodetector; the first photodetector instructs the workpiece stage to focus and level according to the second diffracted light; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light; In the second working mode, the second push-pull structure is used to move the second grating out of the light incident side of the first photodetector, and the first photodetector receives the light beam reflected by the wafer surface.

7. The measuring system according to any one of claims 1 to 4, characterized in that: The detection structure includes a first photodetector, a second photodetector, and a second grating; In the first working mode, the second grating receives the first diffracted light reflected by the wafer surface, and incidents the second diffracted light onto the first photodetector; the first photodetector instructs the workpiece stage to focus and level according to the second diffracted light; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light; In the second operating mode, the second photodetector receives the light beam reflected by the wafer surface.

8. The measuring system according to claim 7, characterized in that The detection structure also includes a second semi-transparent and semi-reflective mirror; The second semi-transparent and semi-reflective mirror is used to: in the first working mode, transmit the first diffracted light reflected by the wafer surface to the second grating; in the second working mode, reflect the light beam reflected by the wafer surface to the second photodetector.

9. The measuring system according to any one of claims 1 to 8, characterized in that: In the first working mode, the detection structure is used to generate a first indication signal according to the first diffracted light, and send the first indication signal to the workpiece stage; The workpiece stage is used to perform focusing and leveling according to the first indication signal; In the second working mode, the detection structure is used to generate a second indication signal according to the light beam, and send the second indication signal to the workpiece stage; The workpiece stage is used for aligning according to the second indication signal.

10. The measuring system according to any one of claims 1 to 9, characterized in that: In the second working mode, the detection structure is further used to instruct the workpiece stage to perform coarse alignment according to the light beam; and / or, In the first working mode, the detection structure is further used to adjust the focal distance between the detection structure and the wafer surface according to the first diffracted light.

11. A lithography apparatus, characterized in that: It comprises an exposure light source, a mask stage, a lens system, a workpiece stage and the measurement system according to any one of claims 1 to 10, wherein the workpiece stage is used to carry a wafer; The lens system is arranged between the light source structure and the detection structure, and the lens system is arranged opposite to a preset detection position in the wafer for focusing, leveling and alignment; When the wafer is photolithographically processed, the light emitted by the exposure light source is projected onto the mask to form a light projection pattern; The lens system receives the light projection pattern and projects the light projection pattern onto the wafer.

12. A measurement method of a measurement system, characterized in that: The measuring system comprises a light source structure and a detection structure, wherein the light source structure comprises a light source and a first grating; and the measuring method comprises: The light source is used to emit a light beam, and the light beam passes through the first grating to form a first diffracted light, and the first diffracted light is incident on the surface of the wafer on the work stage; the detection structure is used to receive the first diffracted light reflected by the wafer surface, and the work stage is instructed to focus and level according to the received first diffracted light; The light source is used to emit the light beam, and the light beam is incident on the wafer surface of the workpiece stage; the detection structure is used to receive the light beam reflected by the wafer surface, and the workpiece stage is instructed to align according to the received light beam.

13. The measuring method according to claim 12, characterized in that: The light source structure further includes a first push-pull structure, and the light source includes a first light source; The method of using the light source to emit a light beam, and the light beam passing through the first grating to form a first diffracted light, comprises: The first push-pull structure is used to move the first grating to the light-emitting side of the first light source; the first light source is used to emit the light beam, and the light beam passes through the first grating to form the first diffracted light; The light beam is emitted by the light source, and the light beam is incident on the wafer surface of the workpiece stage, comprising: The first push-pull structure is used to move the first grating out of the light-emitting side of the first light source; the first light source is used to emit the light beam, and the light beam is incident on the surface of the wafer on the workpiece stage.

14. The measuring method according to claim 12, characterized in that: The light source comprises a first light source and a second light source, and the first grating is located at a light-emitting side of the first light source; The method of using the light source to emit a light beam, and the light beam passing through the first grating to form a first diffracted light, comprises: Using the first light source to emit the light beam, the light beam passes through the first grating to form the first diffracted light; The light beam is emitted by the light source, and the light beam is incident on the wafer surface of the workpiece stage, comprising: The light beam is emitted by the second light source, and the light beam is incident on the wafer surface of the workpiece stage.

15. The measuring method according to claim 14, characterized in that: The light source structure also includes a first semi-transparent and semi-reflective mirror; The first diffracted light emitted from the first grating is transmitted by the first semi-transparent and semi-reflective mirror, and the light beam emitted from the second light source is reflected by the first semi-transparent and semi-reflective mirror, so that the first diffracted light and the light beam are incident on the workpiece stage along the same optical path.

16. The measuring method according to any one of claims 12 to 15, characterized in that: The detection structure includes a first photodetector; The step of using the detection structure to receive the first diffracted light reflected by the wafer surface, and instructing the workpiece stage to perform focusing and leveling according to the received first diffracted light, comprises: Using the first photodetector to receive the first diffracted light reflected by the surface of the wafer, and instructing the workpiece stage to perform focusing and leveling according to the received first diffracted light; The step of using the detection structure to receive the light beam reflected from the wafer surface and instructing the workpiece stage to align according to the received light beam comprises: The first photodetector is used to receive the light beam reflected by the wafer surface, and the workpiece stage is instructed to align according to the received light beam.

17. The measuring method according to any one of claims 12 to 15, characterized in that: The detection structure includes a first photodetector, a second push-pull structure, and a second grating; The step of using the detection structure to receive the first diffracted light reflected by the wafer surface, and instructing the workpiece stage to perform focusing and leveling according to the received first diffracted light, comprises: The second push-pull structure is used to move the second grating to the light incident side of the first photodetector; the second grating is used to receive the first diffracted light reflected by the wafer surface, and the second diffracted light is incident on the first photodetector; the first photodetector is used to instruct the workpiece stage to focus and level according to the received second diffracted light; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light; The step of using the detection structure to receive the light beam reflected from the wafer surface and instructing the workpiece stage to align according to the received light beam comprises: The second push-pull structure is used to move the second grating out of the light incident side of the first photodetector; the light beam reflected from the wafer surface is received by the first photodetector, and the workpiece stage is instructed to align according to the received light beam.

18. The measuring method according to any one of claims 12 to 15, characterized in that: The detection structure includes a first photodetector, a second photodetector, and a second grating; The step of using the detection structure to receive the first diffracted light reflected by the wafer surface, and instructing the workpiece stage to perform focusing and leveling according to the received first diffracted light, comprises: The first diffracted light reflected by the wafer surface is received by the second grating, and the second diffracted light is incident on the first photodetector; the workpiece stage is instructed to focus and level according to the received second diffracted light by the first photodetector; wherein the number of moiré fringes of the second diffracted light is greater than the number of moiré fringes of the first diffracted light; The step of using the detection structure to receive the light beam reflected from the wafer surface and instructing the workpiece stage to align according to the received light beam comprises: The light beam reflected by the wafer surface is received by a second photodetector, and the workpiece stage is instructed to align according to the received light beam.

19. The measuring method according to claim 18, characterized in that: The detection structure also includes a second semi-transparent and semi-reflective mirror; The first diffracted light reflected from the wafer surface is transmitted to the second grating by the second semi-transparent and semi-reflective mirror, and the light beam reflected from the wafer surface is reflected to the second photodetector by the second semi-transparent and semi-reflective mirror.

20. The measuring method according to any one of claims 12 to 19, characterized in that: The detection structure instructs the workpiece stage to perform focusing and leveling according to the received first diffracted light, including: Using the detection structure to receive the first diffracted light, and imaging the first diffracted light into a first image including moiré fringes; The detection structure is used to obtain a focus offset according to the preset position information of the preset detection position in the first image and the wafer surface, and the focus offset is sent to the work stage, and the work stage instructs the work stage to focus according to the focus offset; and the detection structure is used to obtain a first distance and a first height difference between multiple first target detection points in the first direction of the first image, and a first leveling offset is obtained according to the first distance and the first height difference, and the first leveling offset is sent to the work stage, and the work stage instructs the work stage to level in the first direction according to the first leveling offset; and the detection structure is used to obtain a second distance and a second height difference between multiple second target detection points in the second direction of the first image, and a second leveling offset is obtained according to the second distance and the second height difference, and the second leveling offset is sent to the work stage, and the work stage instructs the work stage to level in the second direction according to the second leveling offset; wherein, in the first image, the first direction is perpendicular to the second direction.

21. The measuring method according to any one of claims 12 to 20, characterized in that: The light beam received by the detection structure instructs the workpiece stage to align, including: receiving the light beam by using the detection structure, and imaging the light beam into a second image; The second image is matched with a preset image of a preset detection position on the workpiece stage by the detection structure to obtain an alignment offset, and the workpiece stage is instructed to align according to the alignment offset.

22. The measuring method according to any one of claims 12 to 21, characterized in that: The light source is used to emit a light beam, the light beam passes through the first grating to form a first diffracted light, and the first diffracted light is incident on the surface of the wafer on the workpiece stage; Before using the detection structure to receive the first diffracted light reflected by the wafer surface and instructing the workpiece stage to perform focusing and leveling according to the received first diffracted light, the correction method further includes: The light source is used to emit the light beam, and the light beam is incident on the wafer surface of the workpiece stage; the detection structure is used to receive the light beam reflected by the wafer surface, and the workpiece stage is instructed to perform coarse alignment according to the received light beam; and / or, The light source is used to emit the light beam, and the light beam is incident on the wafer surface of the workpiece stage; the detection structure is used to receive the light beam reflected by the wafer surface, and before the workpiece stage is instructed to align according to the received light beam, the correction method further includes: The light source is used to emit a light beam, which passes through the first grating to form a first diffracted light, and the first diffracted light is incident on the surface of the wafer on the workpiece stage; the detection structure is used to receive the first diffracted light reflected by the wafer surface, and the focal length between the detection structure and the wafer surface is adjusted according to the received first diffracted light.

Images