Light spot calibration method, optical detection system and storage medium

Abstract

The invention discloses a light spot calibration method, an optical detection system and a storage medium. The light spot calibration method comprises the following steps: acquiring a first position of a light spot formed by an illumination light beam in an irradiation area; the transmission direction of the illumination light beam is adjusted until the first position of the light spot meets a first preset condition, and the calibration piece is moved into the irradiation area and located on the imaging focal plane; acquiring state information of the light spot on the surface of the calibration piece, wherein the state information comprises at least one of a second position, an angle, a size and uniformity; positioning precision of the second position is higher than that of the first position; shaping the illumination beam until the state information of the light spot meets a second preset condition, and moving the calibration piece out of the irradiation area; acquiring the optical power of a light spot formed by the illumination beam in the irradiation area, and adjusting the attenuation of the illumination beam until the optical power of the light spot meets a third preset condition; and the calibrated light spot is used for optical detection of the calibration piece. According to the invention, automatic calibration of light spots can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of detection equipment, and in particular to a light spot calibration method, an optical detection system and a storage medium. Background Art

[0002] In optical inspection equipment, an illumination beam is usually used to form a detection spot on the object to be tested, and feature detection is performed by collecting the reflected light or scattered light of the spot. The optical characteristics of the spot (such as light power, uniformity, shape, etc.) will directly affect the detection effect. Therefore, in specific inspection projects, the spot needs to be calibrated.

[0003] At present, the light spot still mainly relies on manual calibration. This method has low calibration efficiency and low calibration accuracy, which restricts the performance of optical detection equipment. There is an urgent need to improve this situation. Summary of the invention

[0004] The main technical problem solved by the present invention is the low efficiency of manually calibrating the light spot and the limited performance of the equipment.

[0005] According to the first aspect, an embodiment provides a light spot calibration method, comprising:

[0006] Acquire a first position of a light spot formed by the illumination light beam in the irradiated area;

[0007] Adjusting the transmission direction of the illumination light beam until a first preset condition is satisfied at a first position of the light spot, and moving the calibration piece into the irradiation area and in the imaging focal plane;

[0008] Acquiring state information of the light spot on the surface of the calibration piece, the state information including at least one of a second position, an angle, a size, and uniformity; the positioning accuracy of the second position is higher than that of the first position;

[0009] Shaping the illumination beam until the state information of the light spot meets the second preset condition, and moving the calibration piece out of the irradiation area;

[0010] Acquire the optical power of the light spot formed by the illumination light beam in the irradiated area, and adjust the attenuation of the illumination light beam until the optical power of the light spot meets the third preset condition;

[0011] The calibrated light spot is obtained and used for optical detection of the calibration part.

[0012] According to the second aspect, an optical detection system is provided in one embodiment, comprising:

[0013] A light source for generating an illumination beam;

[0014] A pointing stabilization module is provided on the outgoing light path of the light source and is used to adjust the light path direction of the illumination light beam;

[0015] A power adjustment module is provided on the outgoing light path of the pointing stabilization module and is used to adjust the attenuation of the illumination light beam;

[0016] A beam shaping module is provided on the outgoing light path of the pointing stabilization module and is used to adjust the pitch and / or yaw of the illumination beam and the diffraction state;

[0017] A light beam detection device, used to obtain a first position of a light spot formed by the illumination light beam in the irradiation area;

[0018] Power detection equipment, used to detect the optical power of the light spot;

[0019] A motion platform, used for driving the calibration piece to move along a preset motion direction;

[0020] An image detector, used to obtain state information of the light spot on the surface of the calibration piece; the state information includes at least one of a second position, an angle, a size, and uniformity; the positioning accuracy of the second position is higher than that of the first position;

[0021] The processing module is used to control the pointing stabilization module to adjust the transmission direction of the illumination light beam until the first position of the light spot obtained by the light beam detection device meets the first preset condition; it is also used to control the motion platform to move the calibration piece into or out of the irradiation area; it is also used to control the beam shaping module to shape the illumination light beam until the state information of the light spot obtained by the image detector meets the second preset condition; it is also used to control the power adjustment module to adjust the attenuation of the illumination light beam until the light power of the light spot obtained by the power detection device meets the third preset condition; and perform optical detection of the calibration piece based on the calibrated light spot.

[0022] According to a third aspect, an embodiment provides a computer-readable storage medium, on which a program is stored, and the program can be executed by a processor to implement the method described in the first aspect.

[0023] According to the light spot calibration method, optical detection system and storage medium of the above-mentioned embodiments, by acquiring the first position of the light spot, after the first position reaches the standard, the calibration piece is imaged to the focal plane and the light spot status information is detected, and after the status information reaches the standard, the optical power is calibrated. This application improves mechanical automation by establishing a multi-step detection and calibration process to achieve automatic calibration of the light spot, thereby improving the efficiency and accuracy of the light spot calibration and being able to effectively improve the performance of the optical detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the position of a light spot provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of the state information of a light spot provided by an embodiment of the present application;

[0026] Figure 3 A schematic diagram of the structure of an optical detection system provided in one embodiment of the present application (I);

[0027] Figure 4 A schematic diagram of the structure of a pointing stabilization module provided in one embodiment of the present application;

[0028] Figure 5 A schematic diagram of the structure of a variable attenuation module provided in one embodiment of the present application;

[0029] Figure 6 A schematic diagram of the structure of a beam shaping module provided in one embodiment of the present application;

[0030] Figure 7 A schematic diagram of obtaining a first position of a light spot provided by an embodiment of the present application;

[0031] Figure 8 A schematic diagram of obtaining the optical power of a light spot provided by an embodiment of the present application;

[0032] Fig. 9 A schematic diagram of the structure of an optical detection system provided in one embodiment of the present application (II);

[0033] Fig.10 A schematic diagram of the structure of a shutter module provided in one embodiment of the present application;

[0034] Fig.11 A schematic diagram of the structure of a polarization switching module provided in one embodiment of the present application;

[0035] Fig.12 A flow chart of a spot calibration method provided in one embodiment of the present application (I);

[0036] Fig.13 Flow chart (II) of a light spot calibration method provided in one embodiment of the present application;

[0037] Fig.14 Flow chart of a spot calibration method provided in one embodiment of the present application (III);

[0038] Fig.15 Flowchart (IV) of a spot calibration method provided for one embodiment of the present application.

[0039] Figure numerals: 1-light source; 2-pointing stabilization module; 3-shutter module; 4-power adjustment module; 41-variable attenuation module; 42-fixed attenuation module; 5-variable beam expansion module; 6-polarization switching module; 7-beam shaping module; 8-beam detection device; 9-power detection device; 10-image detector; 101-imaging module; 11-motion platform; 12-processing module; 100-calibration component. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0041] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0042] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0043] like Figure 1 As shown, in the field of optical inspection, the detection spot needs to be irradiated at a preset position to detect the features to be tested on the test piece. The position of the spot needs to be within the theoretical area so that the features to be tested can generate corresponding reflected light or scattered light, and finally achieve the detection effect. Among them, the test piece can be a product that needs to be inspected on the surface, such as a wafer, a display panel or a glass screen, and the features to be tested can correspond to the processing pattern of the wafer, a display unit, a surface defect, etc.

[0044] like Figure 2As shown, in general, in order to improve the detection efficiency, optical detection often adopts the form of linear light spot. The ideal light spot is a long elliptical shape. Therefore, the circular illumination light beam needs to be processed to obtain the required detection light spot. After a series of optical processing such as shaping and focusing the illumination light beam generated by the light source, a light spot will be formed when the light beam is irradiated on the surface of the test piece. In order to achieve accurate detection effects, the state information (or characteristic information) of the light spot needs to meet the design requirements. The state information can include information such as position, uniformity, size, and angle. As Figure 2 As shown in (A), after the illumination beam is shaped and focused, the light intensity inside and outside the spot may be different. At this time, the actual uniformity of the spot may not meet the requirements. Figure 2 As shown in (B) in the figure, after the illumination beam is shaped and focused, the size of the light spot will change, and there will be a deviation between the actual size and the preset size. Figure 2 As shown in (C) in the figure, after the illumination beam is processed by refraction, reflection, focusing, etc., there is a deviation between the actual angle of the light spot and the preset angle. Figure 2 As shown in (D), generally speaking, there is a difference between the actual uncalibrated light spot and the ideal light spot, and the state information of the light spot generally needs to be calibrated to meet the detection requirements.

[0045] In order to improve the efficiency and accuracy of light spot calibration, an embodiment of the present application provides an optical detection system, in which multiple optical functional modules are mechanically adjusted through controllable mechanical actuators (displacement actuators or rotation actuators), etc., thereby reducing the involvement of manual adjustment, providing mechanical automation, realizing automatic calibration of the light spot, and improving the efficiency and accuracy of light spot calibration.

[0046] like Figure 3 As shown, the optical detection system provided by the present application may include: a light source 1, a pointing stabilization module 2, a power adjustment module 4, a beam shaping module 7, a beam detection device 8, a power detection device 9, a motion platform 11 and a processing module 12.

[0047] The light source 1 is used to generate an illumination beam; according to the actual detection item, the light source 1 can be an infrared light, ultraviolet light or white light source, etc. For example, the embodiment of the present application uses a laser beam, and the specific wavelength is determined according to the actual detection requirements.

[0048] The pointing stabilization module 2 is arranged on the outgoing optical path of the light source 1, and is used to adjust the optical path direction of the illumination beam. For example, the pointing stabilization module 2 may include optical elements such as a reflector and a beam splitter, and the optical path direction of the illumination beam may be changed by changing the spatial angle of the reflector or the beam splitter through the actuator.

[0049] For example, Figure 4As shown, the illumination light beam is divided into two branches through two beam splitters, and the spot images of the light beams of the two branches are acquired respectively through the detectors. The two branches obtain the positions of the centers of the two spots. In the ideal light path direction, the two branches have two ideal spot positions. Alternatively, a position is manually calibrated, or the position corresponding to the light path direction that meets the detection requirements (such as the detection after the last spot calibration) is used as the ideal spot position. The actual positions measured by the two detectors are obtained and compared with the ideal positions. When the two meet the error range, it can be determined that the current light path direction meets the requirements. Figure 4 On the basis of, a reflector can be provided before the optical path of the first beam splitter on the left, and the illumination light beam is reflected by the reflector and then enters the beam splitter. According to the current direction of the optical path, the reflector can be controlled to rotate to adjust the direction of the optical path.

[0050] The power adjustment module 4 is arranged on the outgoing light path of the pointing stabilization module 2, and is used to adjust the attenuation of the illumination light beam. For example, the power adjustment module 4 may include a half-wave plate and a polarizer. When the linear polarized light passes through the half-wave plate and the polarizer, the continuous adjustment of the optical power is achieved by changing the polarization direction. It may also include an optical device such as a filter to achieve equal attenuation. In some embodiments, the power adjustment module 4 may also include a metering device such as a power meter to detect the real-time attenuation.

[0051] For example, Figure 5 As shown, the polarizer can be a Brewster angle thin film polarizer. The Brewster angle thin film polarizer can only reflect S polarized light and transmit P polarized light. When the half-wave plate is rotated by a certain angle θ, the polarization direction of the linear polarized light is rotated by 2θ. At this time, the light energy in the S polarized direction of the linear polarized light passing through the half-wave plate is reflected into the subsequent optical path, and the other part passes through the thin film polarizer and does not enter the subsequent optical path. Therefore, the power of the subsequent optical path is attenuated, and it can be attenuated continuously.

[0052] The beam shaping module 7 is arranged on the outgoing light path of the pointing stabilization module 2, and is used to adjust the pitch and / or yaw of the illumination beam, as well as the diffraction state. For example, the beam shaping module 7 may include a plurality of deflectable beam splitters, and the deflection angle adjustment of multiple axes is realized through the actuator to adjust the pitch and / or yaw of the illumination beam. It may also include diffractive optical elements (DOE) for beam shaping, such as homogenization, collimation, focusing, and forming a specific pattern. Figure 6 As shown, a beam splitter and a detector may be arranged on the optical path before and after the DOE to measure the direction of the optical path.

[0053] The light beam detection device 8 is used to obtain the first position of the light spot formed by the illumination light beam in the irradiation area; for example, Figure 7 As shown, the beam detection device 8 can be a beam quality analyzer. When the illumination beam is irradiated on the front of the calibration piece 100, there is an irradiation area on the surface of the calibration piece 100. The light spot is formed in this area. When it is necessary to obtain the first position of the light spot, the beam quality analyzer is moved to the position corresponding to the irradiation area to obtain the first position of the light spot. Alternatively, the irradiation area can be understood as the area where the illumination beam intersects with the imaging focal plane.

[0054] It should be noted that the calibration piece 100 in the embodiment of the present application can be a piece to be tested, or a device corresponding to the previous and next processes of the piece to be tested, or a device designed and processed according to the calibration needs. Taking the production of semiconductor devices as an example, not every wafer in each process needs to be tested. Generally speaking, only the wafer shape that needs to be tested is called a piece to be tested. In the embodiment of the present application, it can be a shape corresponding to any processing step of the wafer, so as to meet the spot calibration. For another example, taking flat glass as an example, the finished flat glass is smooth, the piece to be tested is the finished flat glass, and the calibration piece can be the flat glass in the processed state. The embodiment of the present application does not limit the specific form of the specific calibration piece 100.

[0055] The power detection device 9 is used to detect the optical power of the light spot; for example, Figure 8 As shown, the power detection device 9 may be a power meter. When the illumination light beam is irradiated on the front of the calibration piece 100, the power meter is moved to a position corresponding to the irradiated area to obtain the optical power of the light spot.

[0056] The motion platform 11 is used to drive the calibration piece 100 to move in space; the motion platform 11 can have a bearing and a moving function, and while carrying the calibration piece 100, it drives the calibration piece 100 to move up and down, rotate, or move in a plane, so that the light spot can be irradiated on the area to be detected of the calibration piece 100.

[0057] The image detector 10 is used to obtain status information of the light spot on the surface of the calibration piece 100; the status information may include at least one of a second position, an angle, a size, and uniformity; the positioning accuracy of the second position is higher than that of the first position.

[0058] For example, the image detector 10 can be a linear scan camera. During a line scan, the output signal of the camera pixel is transmitted with a delay and added line by line to form a cumulative image. In this way, during the target movement, the camera can obtain multiple integral images, thereby reducing noise and improving image contrast. The linear scan camera can capture the surface of the calibration piece 100 to form a detection image, and the processing module can obtain the above-mentioned state information by analyzing the detection image. For example, a TDI camera can achieve high-speed shooting and scenes with high requirements for image quality and sensitivity.

[0059] In some embodiments, the optical detection system may further include an imaging module 101, which may include an imaging lens group, which collects signal light generated by scattering / reflection on the surface of the calibration piece 100, and projects the image of the surface of the calibration piece 100 to the image detector 10, which realizes the image acquisition of the surface of the calibration piece 100. The imaging lens group has an imaging focal plane. Since the imaging module may also be maintained or replaced, and the focusing may also be adjusted during use, the above situations will cause the focal plane to change. Therefore, re-determining the imaging focal plane is conducive to obtaining a more accurate spot image and is conducive to automatic spot calibration. Here, the imaging module 101 can use an objective lens to realize microscopic imaging of the surface of the calibration piece 100.

[0060] The processing module 12 is used to control the pointing stabilization module to adjust the transmission direction of the illumination beam until the first position of the light spot obtained by the light beam detection device satisfies the first preset condition; it is also used to control the motion platform to move the calibration piece into or out of the irradiation area; it is also used to control the beam shaping module to shape the illumination beam until the state information of the light spot obtained by the image detector satisfies the second preset condition; it is also used to control the power adjustment module to adjust the attenuation of the illumination beam until the light power of the light spot obtained by the power detection device satisfies the third preset condition; and perform optical detection of the calibration piece based on the calibrated light spot. The processing module 12 can be implemented by a processor or a terminal device, etc., and can control various devices and functional modules of the optical detection system, and adjust the light spot by detecting the first position and state information of the light spot, thereby realizing automatic calibration of the light spot.

[0061] In some embodiments, such as Fig. 9 As shown, the optical detection system may further include a shutter module 3, which is disposed on the outgoing light path pointing to the stabilization module 2 and is used to shut off or open the light path of the illumination light beam.

[0062] For example, Fig.10 As shown, the shutter module 3 may include a half-wave plate, a Pockels cell and a Brewster angle thin film polarizer. The illumination light beam passes through the half-wave plate, the Pockels cell and the Brewster angle thin film polarizer in sequence. Assuming that the polarization state of the light passing through the half-wave plate is a fixed S polarization, when no voltage is applied to the Pockels cell, the light is still S polarized after passing through the Pockels cell. When voltage is applied to the Pockels cell, the Pockels cell will change the polarization state of the light to P polarization. At this time, when the light is incident on the Brewster angle thin film polarizer at the rear, the light will pass through the polarizer without reflection, so there is no light in the subsequent optical path, thus realizing the function of the shutter.

[0063] For example, a mobile light-blocking method can be used, in which an actuator is used to drive a light-absorbing element to block light to achieve the shutter effect. However, if the shutter opening and closing frequency is required to be higher, an ordinary mechanical shutter cannot be used (up to the ms level), while the response time of the Pockels cell can be up to the us or ns level.

[0064] In some embodiments, the power adjustment module 4 may include: a variable attenuation module 41 and a fixed attenuation module 42 .

[0065] The variable attenuation module 41 is arranged on the outgoing light path pointing to the stabilizing module 2, and is used to adjust the attenuation of the illumination light beam; for example, the variable attenuation module 41 can be adopted as follows Figure 5 The implementation method of the half-wave plate and the polarizer is shown.

[0066] The fixed-multiple attenuation module 42 is arranged on the outgoing optical path of the beam shaping module 7, and is used to attenuate the illumination beam by a preset magnification. For example, the fixed-multiple attenuation module 42 may include a plurality of fixed-multiple filters, and the filters are cut into and out of the optical path by the actuator to achieve fixed-multiple attenuation of the beam.

[0067] In some embodiments, such as Fig. 9 As shown, the optical detection system may further include a variable magnification beam expansion module 5 and a polarization switching module 6.

[0068] The variable magnification and beam expansion module 5 is arranged on the output light path of the variable attenuation module 41, and is used to adjust the diameter of the illumination light beam; for example, the variable magnification and beam expansion module 5 may include a variable magnification lens group, and by changing the relative position of the lenses in the variable magnification lens group, different magnifications of the light beam can be expanded, such as expanding it to 1 to 3 times the original.

[0069] The polarization switching module 6 is arranged on the outgoing light path of the variable magnification beam expansion module 5, and is used to change the polarization state of the illumination beam. Fig.11 As shown, the polarization switching module 6 may include a rotating disk and a plurality of wave plates of different models and polarization directions. For example, by cutting one of the three wave plates on the rotating disk into the light path, polarization adjustment in a specific direction (such as C polarization, S polarization, P polarization, etc.) can be achieved.

[0070] Although the above-mentioned functional modules provide some specific implementation methods, the present application does not limit the specific hardware. The main purpose is to implement the functions and controllable drive thereof, so as to realize automatic calibration of the light spot and reduce the involvement of manual calibration.

[0071] The following is an explanation of the specific process of the spot calibration method for the optical detection system. Fig.12 As shown, the spot calibration method may include the following steps:

[0072] Step 1, obtain the first position of the light spot formed by the illumination light beam in the irradiated area. For example, the first position of the light spot is obtained by the light beam detection device 8. The positioning accuracy of the first position obtained by the light beam detection device 8 is lower than the positioning accuracy by the image detector 10. For example, the light beam quality analyzer is highly sensitive to light intensity, so the error of the center of the light spot obtained by fitting is large. Therefore, relying on the light beam quality analyzer is only a rough positioning of the light spot position. When the first position needs to be calibrated, it is defined as a coarse calibration. However, in order to realize the detection of subtle features to be measured, the imaging area of ​​the image detector 10 through the imaging module is relatively small, and the initial position of the light spot on the calibration piece may be outside its imaging area, and the first position cannot be obtained by the image detector 10. Therefore, the present application obtains the first position through the light beam detection device 8.

[0073] In some embodiments, such as Fig.13 As shown, before obtaining the first position of the light spot formed by the illumination light beam in the irradiation area, the method may also include:

[0074] Step 110, select the calibration category of the light spot, which may include a first calibration category (such as laser spot change) and a second calibration category (such as routine maintenance); in the first calibration category, the position of the light spot generated by the light source 1 is not calibrated; in the second calibration category, the position of the light spot provided by the light source 1 last time meets the first preset condition. For example, in the first calibration category, the hardware related to the generation of the light source 1 or the light path propagation in the optical detection system has changed, such as when the light source 1, the pointing stabilization module 2, and the beam shaping module 7 are replaced or repaired, and the position of the light spot has changed unpredictably compared with the last detection, and needs to be roughly calibrated. In the second calibration category, the hardware related to the generation of the light source 1 or the light path propagation in the optical detection system has not changed, and the position of the light spot is predictable compared with the last detection. For example, the optical detection system has only undergone routine maintenance, and no rough calibration is required at this time.

[0075] Step 120 : When the first calibration category is selected, the optical path of the illumination light beam is configured, and the first position of the light spot formed by the illumination light beam in the irradiated area is acquired by using the optical detection device 8 .

[0076] Step 130: When the second calibration category is selected, it is assumed that the first position of the light spot formed by the illumination light beam in the irradiation area satisfies the first preset condition.

[0077] Before performing spot calibration, the user can select the corresponding calibration category (such as laser spot change or routine maintenance) based on the last use of the optical detection system to avoid repeated rough calibration.

[0078] In some embodiments, in step 120, obtaining a first position of a light spot formed by the illumination beam in the irradiation area by configuring the light path of the illumination beam may include:

[0079] Step 121: Control the shutter module 3 to cut off the light path of the illumination light beam.

[0080] Step 122: Control the attenuation of the variable attenuation module 41 to configure the optical power of the illumination beam to be lower than the first test power. If OP represents the optical power, the first test power can be configured to be OP0. At this time, the optical power of the illumination beam configured by attenuation is OP0. min At a power lower than the first test power OP0.

[0081] Step 123: Control the fixed-power attenuation module 42 to move into the optical path of the illumination light beam.

[0082] Step 124: Move the light beam detection device 8 to the irradiation area, and the light beam detection device 8 is used to obtain the first position of the light spot.

[0083] Step 125 , control the shutter module 3 to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the light beam detection device 8 .

[0084] This is because the beam quality analyzer is highly sensitive to light intensity. When obtaining the first position of the light spot, the light power of the light spot is reduced to reduce the error of the light spot center obtained by fitting, thereby improving the positioning accuracy of the first position. The light power of the illumination beam can be initially reduced by the variable attenuation module 41. When the variable attenuation module 41 cannot reduce the light power to below the first test power, the fixed-multiple attenuation module 42 can be used to further reduce the light power. After the light power adjustment is completed, the optical path is connected through the shutter module 3, and the illumination beam is irradiated to the beam detection device 8.

[0085] Step 2: adjust the transmission direction of the illumination light beam until the first preset condition is met at the first position of the light spot, and move the calibration piece 100 into the irradiation area and place it at the imaging focal plane.

[0086] In some embodiments, such as Fig.13 As shown, adjusting the transmission direction of the illumination light beam until the first preset condition is satisfied at the first position of the light spot may include:

[0087] Step 201, determine whether the first position of the light spot meets the first preset condition. For example, in the last detection, the light spot position that meets the first preset condition is recorded by the light beam detection device 8 as the preset reference position (x0, y0), and the actual first position of the current light spot is (x1, y1). A deviation range can be preset to determine whether the first position meets the first preset condition.

[0088] Step 202: When the first position of the light spot does not satisfy the first preset condition, it is determined whether the illumination light beam has a preset pointing state.

[0089] That is to say, the current position deviation is analyzed to determine whether the first position does not meet the first preset condition due to the pointing stabilization module 2 or the beam shaping module 7. Figure 4 As shown, the deviation between the actual light path pointing and the theoretical light path pointing can be determined based on the data measured by the two detectors in the pointing stabilization module 2. If the deviation meets the requirement, it is considered that the illumination light beam has a preset pointing state.

[0090] Step 203: When the illumination light beam does not have a preset pointing state, control the pointing stabilization module 2 to adjust the light path pointing of the illumination light beam until it reaches a preset pointing state.

[0091] like Figure 4 As shown, when the illumination light beam does not have a preset directional state, the actuator drives optical elements such as a beam splitter or a reflector to rotate, thereby adjusting the direction of the light path.

[0092] Step 204: When the illumination light beam has a preset pointing state, control the beam shaping module 7 to adjust the pitch and / or yaw of the illumination light beam, that is, adjust the spatial mechanical axis of the optical element in the beam shaping module 7 until the first position of the light spot meets the first preset condition.

[0093] When the illumination beam has a preset directional state, it indicates that it is caused by the beam shaping module 7, such as Figure 5 As shown, the first position can be adjusted by adjusting the pitch and / or yaw of the DOE.

[0094] In step 2, the state information of the light spot needs to be calibrated. At this time, the optical power needs to meet the first test power requirement. At this time, the fixed attenuation module 42 is not needed for fixed attenuation, and the variable attenuation module 41 is used to implement optical power adjustment.

[0095] In some embodiments, the calibration piece 100 may include a first type of calibration piece and a second type of calibration piece, the first type of calibration piece has a preset feature, the second type of calibration piece does not have a preset feature and has a uniform granularity on the surface. For example, taking a wafer as an example, it can be divided into a bare wafer (unprocessed, which can be called a haze wafer) and a processed wafer (with a processed pattern on the surface, which can be called a pattern wafer). The wafer with a pattern is easier to focus and can be used to determine the position of the imaging focal plane. The surface of the bare wafer has a uniform granularity, and the spot image will not be disturbed by the processed pattern, which can facilitate the acquisition of the shape and uniformity of the spot.

[0096] In some embodiments, in step 2, before moving the calibration piece 100 into the irradiation area, the following steps may also be included:

[0097] Step 211: Control the shutter module 3 to cut off the light path of the illumination light beam.

[0098] Step 212: Control the fixed-multiple attenuation module 42 to move out of the optical path of the illumination light beam.

[0099] Step 213, control the attenuation of the variable attenuation module 41 so that the optical power of the configured illumination beam reaches the first test power. If OP represents the optical power, the first test power can be configured as OP0. At this time, the optical power of the illumination beam configured by attenuation is OP0.

[0100] Step 214: Move the first type calibration piece into the irradiation area.

[0101] Step 215: Control the shutter module 3 to open the optical path of the illumination light beam, so that the illumination light beam is irradiated to the first type calibration component.

[0102] In some embodiments, in step 2, moving the calibration piece 100 into the irradiation area and placing it at the imaging focal plane may include:

[0103] Step 221: Control the first type calibration component to move in a direction perpendicular to the imaging focal plane.

[0104] Step 222, control the image detector 10 to continuously capture images of the first type calibration piece on the irradiated area, obtain the spatial position of the imaging focal plane according to the imaging result, and when the image is clearest, it is considered that the first type calibration piece is in the imaging focal plane.

[0105] Step 223, move the first type of calibration piece out of the irradiation area, and move the second type of calibration piece into the irradiation area and reach the spatial position of the imaging focal plane. Since the spatial position of the imaging focal plane has been obtained before, the second type of calibration piece can be directly moved to the imaging focal plane.

[0106] The status information of the light spot is easier to measure in the second type of calibration piece, but the calibration piece 100 needs to be precisely focused for accurate measurement. The second type of calibration piece is not conducive to focusing. The embodiment of the present application introduces the first type of calibration piece, and searches for the focal plane through the first type of calibration piece with the features to be measured. After determining the focal plane height, the second type of calibration piece is moved to the focal plane position to detect the status information of the light spot.

[0107] Step 3: Obtain state information of the light spot on the surface of the calibration piece 100, where the state information may include at least one of a second position, an angle, a size, and uniformity; the second position has a higher positioning accuracy than the first position. In some embodiments, the state information of the light spot on the surface of the calibration piece 100 is obtained by an image detector 10.

[0108] Step 4: Shape the illumination light beam until the state information of the light spot meets the second preset condition, and move the calibration piece 100 out of the irradiation area.

[0109] like Fig.14 As shown, in step 4, shaping the illumination light beam until the state information of the light spot meets the second preset condition may include:

[0110] When the status information may include a second position and the second preset condition may include preset position information, it is determined whether the second position of the light spot satisfies the preset position information; if not, the beam shaping module 7 is controlled to adjust the pitch and / or yaw of the illumination beam until the second position of the light spot satisfies the preset position information.

[0111] When the state information may include uniformity and the second preset condition may include preset uniformity information, it is determined whether the uniformity of the light spot satisfies the preset uniformity information; if not, the beam shaping module 7 is controlled to adjust the pitch and / or yaw of the illumination beam until the uniformity of the light spot satisfies the preset uniformity information.

[0112] When the state information may include an angle and the second preset condition may include preset angle information, it is determined whether the angle of the light spot satisfies the preset angle information. If not, the diffraction state of the illumination light beam is adjusted by the beam shaping module 7 until the angle of the light spot satisfies the preset angle information.

[0113] When the state information may include size and the second preset condition may include preset size information, it is determined whether the size of the light spot meets the preset size information, and if not, the diffraction state of the illumination light beam is adjusted by the beam shaping module 7 until the size of the light spot meets the preset size information.

[0114] In the adjustment of the above status information, if the number of automatic adjustments exceeds the preset number, a corresponding alarm message is generated, and the user can make manual adjustments according to the alarm message. For example, if the spot uniformity still does not meet the requirements after multiple automatic adjustments, an alarm message corresponding to the spot uniformity is generated. For another example, when the angle or size of the spot does not meet the requirements, an error message can also be reported, and the user can manually adjust the DOE.

[0115] like Figure 2 As shown, the light spot image collected by the image detector 10 is compared with the second preset condition, and the beam shaping module 7 can be adjusted according to the difference to obtain a light spot that meets the requirements.

[0116] Step 5: Obtain the optical power of the light spot formed by the illumination light beam in the irradiated area, and adjust the attenuation of the illumination light beam until the optical power of the light spot meets the third preset condition.

[0117] In some embodiments, before obtaining the optical power of the light spot formed by the illumination light beam in the irradiated area, the following method may be further included:

[0118] Step 500, the current position of the light spot is obtained by the light beam detection device 8, and the current position is used as the preset reference position when judging whether the first position of the light spot meets the first preset condition next time. This is because when the state information of the light spot is adjusted, the second position will change, and the first position corresponding to the preset reference position will change accordingly, so it needs to be recorded.

[0119] When the state information of the light spot meets the requirements, the second position of the light spot meets the corresponding preset conditions. At this time, the position of the light spot is recorded by the light beam detection device 8 as the next preset reference position, so as to detect the first position of the light spot when performing the first calibration category.

[0120] In some embodiments, before recording the current position of the light spot by the light beam detection device 8, the following steps may also be included:

[0121] Step 501: Control the shutter module 3 to cut off the light path of the illumination light beam.

[0122] Step 502: Control the attenuation of the variable attenuation module 41 to configure the optical power of the illumination beam to be lower than the first test power. If OP represents the optical power, the first test power can be configured as OP0. At this time, the optical power of the illumination beam configured by attenuation is OP0. min At a power lower than the first test power OP0.

[0123] Step 503: Control the fixed-power attenuation module 42 to move into the optical path of the illumination light beam.

[0124] Step 504: Move the light beam detection device 8 to the irradiation area. The light beam detection device 8 is used to obtain the current position of the light spot.

[0125] Step 505 , control the shutter module 3 to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the light beam detection device 8 .

[0126] In order to improve the accuracy of the preset reference position, the optical power of the illumination light beam is reduced, for example, by using a minimum output, and then the light beam detection device 8 is used for detection.

[0127] At the same time, the pointing stabilization module 2 can be controlled to record the pointing state of the current illumination beam as the preset pointing state for the next calibration, or the two detectors in the beam shaping module 7 can be used to record the pointing state of the light path.

[0128] In some embodiments, in step 5, before obtaining the optical power of the light spot formed by the illumination light beam in the irradiated area, the following steps may also be included:

[0129] Step 501, controlling the shutter module 3 to cut off the light path of the illumination light beam;

[0130] Step 502, control the attenuation of the variable attenuation module 41 to configure the optical power of the illumination beam to reach the first test power. If OP represents the optical power, the first test power can be configured as OP0. At this time, the optical power of the illumination beam is configured as OP0 through attenuation.

[0131] Step 503: Control the fixed-power attenuation module 42 to move out of the optical path of the illumination light beam.

[0132] Step 504: Move the power detection device 9 to the irradiation area. The power detection device 9 is used to detect the optical power of the light spot.

[0133] Step 505 , control the shutter module 3 to open the optical path of the illumination light beam, so that the illumination light beam irradiates the power detection device 9 .

[0134] In some embodiments, such as Fig.15 As shown, obtaining the optical power of the light spot formed by the illumination light beam in the irradiated area, and adjusting the attenuation of the illumination light beam until the optical power of the light spot meets the third preset condition may include:

[0135] Step 511: Obtain the optical power of the light spot formed by the illumination light beam in the illumination area, and determine whether the deviation between the optical power of the light spot and the first test power is within a preset deviation range.

[0136] Step 512: If not, power compensation is performed on the illumination light beam, and the attenuation of the illumination light beam is adjusted by the variable attenuation module 41 until the deviation between the optical power of the light spot and the first test power is within a preset deviation range.

[0137] Step 513: If yes, then end the calibration of the light spot.

[0138] In the present application, lighting power compensation is achieved by adjusting the variable attenuation module 41 to increase or decrease the light power incident on the calibration component; before power compensation, the power of the variable attenuation is adjusted to the first test power OP0 (calculated value), but at this time the power incident on the calibration component 100 may not be OP0 (measured value), so compensation is required, and if calibration is required, then after the calibration is completed, the power still needs to be adjusted to OP0 (calculated value) again, and then the actual power is measured using a power meter. If the power does not meet the standard, compensation is required.

[0139] Step 6: Obtain the calibrated light spot and use it for optical detection of the calibration piece 100.

[0140] In summary, the light spot calibration method provided in the present application can first obtain the first position of the light spot through coarse positioning, perform focal plane search when the coarse positioning position meets the requirements, and then place the calibration component 100 on the focal plane to accurately detect the state information of the light spot. When the state information meets the standards, the position information of the light spot and the direction information of the light beam are recorded, and finally the optical power is detected and calibrated, so as to realize automatic calibration of the light spot and provide a reference value of the position and pointing state for the next light spot calibration.

[0141] The optical detection system provided in the embodiment of the present application has a variable attenuation module 41 and a fixed attenuation module 42, which can continuously adjust the optical power to meet the needs of power compensation calibration, and can also perform fixed attenuation to improve the accuracy of the first position detection using the light beam detection device 8.

[0142] The present application also realizes the opening and closing of the light path through the shutter module 3. The light path can be closed during the process of adjusting the optical power, switching different types of calibration parts or measuring the first position of the light spot to prevent the light beam from irradiating outside the irradiation area.

[0143] The optical detection system provided by this application can realize automatic calibration of the light spot and improve the detection accuracy and speed by reasonably setting the optical function modules for shaping and directing the illumination beam, and cooperating with the position measurement and power test equipment. It is also equipped with beam expansion and deflection switching function modules to meet the needs of more detection scenarios.

[0144] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

[0145] This document is described with reference to various exemplary embodiments. However, those skilled in the art will recognize that changes and modifications may be made to the exemplary embodiments without departing from the scope of this document. For example, various operating steps and components for performing the operating steps may be implemented in different ways (e.g., one or more steps may be deleted, modified, or incorporated into other steps) depending on the specific application or considering any number of cost functions associated with the operation of the system.

[0146] Although the principles of this invention have been shown in various embodiments, many modifications of structures, arrangements, proportions, elements, materials and components particularly suitable for specific environments and operational requirements can be used without departing from the principles and scope of this invention. The above modifications and other changes or amendments will be included in the scope of this invention.

[0147] The foregoing specific description has been described with reference to various embodiments. However, those skilled in the art will recognize that various modifications and changes can be made without departing from the scope of the present disclosure. Therefore, the consideration of the present disclosure will be illustrative rather than restrictive, and all these modifications will be included in its scope. Similarly, the advantages, other advantages and solutions to the problems of various embodiments have been described above. However, the benefits, advantages, solutions to the problems and any elements that can produce these, or make them more clear, should not be interpreted as critical, necessary or necessary. The term "include" and any other variants used in this article are all non-exclusive inclusions, so that the process, method, article or device including the list of elements not only includes these elements, but also includes other elements that are not explicitly listed or do not belong to the process, method, system, article or device. In addition, the term "coupled" and any other variants used in this article refer to physical connections, electrical connections, magnetic connections, optical connections, communication connections, functional connections and / or any other connections.

[0148] Those skilled in the art will appreciate that many changes may be made to the details of the above-described embodiments without departing from the basic principles of the invention. Therefore, the scope of the present invention should be determined solely by the claims.

Claims

1. A spot calibration method, characterized in that: include: Acquire a first position of a light spot formed by the illumination light beam in the irradiated area; Adjusting the transmission direction of the illumination light beam until a first preset condition is satisfied at a first position of the light spot, and moving the calibration piece into the illumination area and in an imaging focal plane; Acquiring state information of the light spot on the surface of the calibration piece, the state information including at least one of a second position, an angle, a size, and uniformity; the positioning accuracy of the second position is higher than that of the first position; shaping the illumination light beam until the state information of the light spot meets a second preset condition, and moving the calibration piece out of the irradiation area; Acquiring the optical power of the light spot formed by the illumination light beam in the illumination area, and adjusting the attenuation of the illumination light beam until the optical power of the light spot meets a third preset condition; The calibrated light spot is obtained and used for optical detection of the calibration piece.

2. The light spot calibration method according to claim 1, characterized in that: Adjusting the transmission direction of the illumination light beam until a first preset condition is satisfied at a first position of the light spot comprises: Determining whether the first position of the light spot meets a first preset condition; When the first position of the light spot does not satisfy the first preset condition, determining whether the illumination light beam has a preset pointing state; When the illumination light beam does not have the preset pointing state, controlling the pointing stabilization module to adjust the light path pointing of the illumination light beam until the preset pointing state is reached; When the illumination light beam has a preset pointing state, the beam shaping module is controlled to adjust the pitch and / or yaw of the illumination light beam until the first position of the light spot meets a first preset condition.

3. The spot calibration method according to claim 1, characterized in that: Before obtaining the first position of the light spot formed by the illumination light beam in the irradiation area, the method further includes: Selecting a calibration category of the light spot, wherein the calibration category includes a first calibration category and a second calibration category; When the first calibration category is selected, a first position of a light spot formed by the illumination beam in the illumination area is obtained by configuring the light path of the illumination beam; When the second calibration category is selected, it is assumed that the first position of the light spot formed by the illumination light beam in the irradiation area satisfies the first preset condition.

4. The spot calibration method according to claim 3, characterized in that: The method of obtaining a first position of a light spot formed by the illumination beam in an irradiated area by configuring an optical path of the illumination beam comprises: Controlling the shutter module to cut off the light path of the illumination light beam; controlling the attenuation amount of the variable attenuation module to configure the optical power of the illumination light beam to be lower than the first test power; Controlling the fixed-multiple attenuation module to move into the optical path of the illumination light beam; Moving a light beam detection device to the irradiation area, the light beam detection device is used to obtain a first position of the light spot; The shutter module is controlled to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the light beam detection device.

5. The spot calibration method according to claim 1, characterized in that: The calibration piece includes a first type of calibration piece and a second type of calibration piece. The first type of calibration piece has a preset feature, and the second type of calibration piece does not have the preset feature and has a uniform granularity on its surface.

6. The light spot calibration method according to claim 5, characterized in that: Before moving the calibration piece into the irradiation area, the method further includes: Controlling the shutter module to cut off the light path of the illumination light beam; Controlling the fixed-power attenuation module to move out of the optical path of the illumination light beam; Controlling the attenuation amount of the variable attenuation module so that the optical power of the illumination light beam reaches a first test power; moving a first type of calibration piece into the irradiation area; The shutter module is controlled to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the first type calibration component.

7. The light spot calibration method according to claim 6, characterized in that: The step of moving the calibration piece into the irradiation area and placing the calibration piece in the imaging focal plane comprises: Controlling the first type of calibration piece to move in a direction perpendicular to the imaging focal plane; Controlling the image detector to continuously capture images of the first type of calibration piece on the irradiation area, and obtaining the spatial position of the imaging focal plane according to the imaging results; The first type of calibration piece is moved out of the irradiation area, and the second type of calibration piece is moved into the irradiation area and reaches the spatial position of the imaging focal plane.

8. The light spot calibration method according to claim 1, characterized in that: Acquiring state information of the light spot on the surface of the calibration piece by an image detector; Shaping the illumination light beam until the state information of the light spot meets a second preset condition includes: When the state information includes a second position and the second preset condition includes preset position information, determining whether the second position of the light spot satisfies the preset position information, and if not, controlling the beam shaping module to adjust the pitch and / or yaw of the illumination beam until the second position of the light spot satisfies the preset position information; When the state information includes uniformity and the second preset condition includes preset uniformity information, determining whether the uniformity of the light spot satisfies the preset uniformity information, and if not, controlling the beam shaping module to adjust the pitch and / or yaw of the illumination beam until the uniformity of the light spot satisfies the preset uniformity information; When the state information includes an angle and the second preset condition includes preset angle information, determining whether the angle of the light spot satisfies the preset angle information, and if not, adjusting the diffraction state of the illumination light beam through a beam shaping module until the angle of the light spot satisfies the preset angle information; When the state information includes size and the second preset condition includes preset size information, it is determined whether the size of the light spot meets the preset size information; if not, the diffraction state of the illumination light beam is adjusted by a beam shaping module until the size of the light spot meets the preset size information.

9. The light spot calibration method according to claim 1, characterized in that: Before obtaining the optical power of the light spot formed by the illumination light beam in the irradiation area, the method further includes: The current position of the light spot is acquired through a light beam detection device, and the current position is used as a preset reference position when determining whether the first position of the light spot meets a first preset condition next time.

10. The light spot calibration method according to claim 9, characterized in that: Before recording the current position of the light spot by the light beam detection device, the method further includes: Controlling the shutter module to cut off the light path of the illumination light beam; controlling the attenuation amount of the variable attenuation module to configure the optical power of the illumination light beam to be lower than the first test power; Controlling the fixed-multiple attenuation module to move into the optical path of the illumination light beam; Moving a light beam detection device to the irradiation area, the light beam detection device is used to obtain the current position of the light spot; The shutter module is controlled to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the light beam detection device.

11. The light spot calibration method according to claim 1, characterized in that: Before obtaining the optical power of the light spot formed by the illumination light beam in the irradiation area, the method further includes: Controlling the shutter module to cut off the light path of the illumination light beam; Controlling the attenuation amount of the variable attenuation module to configure the optical power of the illumination light beam to reach a first test power; Controlling the fixed-power attenuation module to move out of the optical path of the illumination light beam; Moving a power detection device to the irradiation area, the power detection device is used to detect the optical power of the light spot; The shutter module is controlled to open the optical path of the illumination light beam so that the illumination light beam is irradiated to the power detection device.

12. The light spot calibration method according to claim 1, characterized in that: Acquiring the optical power of a light spot formed by the illumination light beam in the illumination area, and adjusting the attenuation of the illumination light beam until the optical power of the light spot meets a third preset condition, comprising: Obtaining the optical power of the light spot formed by the illumination light beam in the irradiation area, and determining whether the deviation between the optical power of the light spot and the first test power is within a preset deviation range; If not, power compensation is performed on the illumination light beam, and the attenuation of the illumination light beam is adjusted by a variable attenuation module until a deviation between the optical power of the light spot and the first test power is within a preset deviation range; If yes, the calibration of the light spot is terminated.

13. An optical detection system, characterized in that: include: A light source for generating an illumination beam; A pointing stabilization module, disposed on the outgoing light path of the light source, and used to adjust the light path direction of the illumination light beam; A power adjustment module, disposed on the outgoing light path of the pointing stabilization module, for adjusting the attenuation of the illumination light beam; A beam shaping module, arranged on the outgoing light path of the pointing stabilization module, for adjusting the pitch and / or yaw of the illumination beam, as well as the diffraction state; A light beam detection device, used for acquiring a first position of a light spot formed by the illumination light beam in an irradiated area; A power detection device, used to detect the optical power of the light spot; A motion platform, used to drive the calibration piece to move in space; An image detector, used to obtain state information of the light spot on the surface of the calibration piece; the state information includes at least one of a second position, an angle, a size, and uniformity; the positioning accuracy of the second position is higher than that of the first position; A processing module is used to control the pointing stabilization module to adjust the transmission direction of the illumination light beam until the first position of the light spot obtained by the light beam detection device satisfies a first preset condition; it is also used to control the motion platform to move the calibration piece into or out of the irradiation area; it is also used to control the beam shaping module to shape the illumination light beam until the state information of the light spot obtained by the image detector satisfies a second preset condition; it is also used to control the power adjustment module to adjust the attenuation of the illumination light beam until the light power of the light spot obtained by the power detection device satisfies a third preset condition; and perform optical detection of the calibration piece based on the calibrated light spot.

14. The optical detection system according to claim 13, characterized in that: It also includes a shutter module, which is arranged on the outgoing light path of the pointing stabilization module and is used to cut off or open the light path of the illumination light beam.

15. The optical detection system according to claim 13, characterized in that: The power adjustment module comprises: A variable attenuation module, disposed on the outgoing light path of the pointing stabilization module, and used for adjusting the attenuation of the illumination light beam; The fixed-multiplication attenuation module is arranged on the outgoing light path of the beam shaping module and is used to attenuate the illumination beam at a preset magnification.

16. The optical detection system according to claim 15, characterized in that: It also includes a zoom beam expansion module and a polarization switching module; The variable magnification beam expansion module is arranged on the outgoing light path of the variable attenuation module, and is used to adjust the diameter of the illumination light beam; The polarization switching module is arranged on the outgoing light path of the variable-power beam expansion module, and is used to change the polarization state of the illumination light beam.

17. A computer-readable storage medium, characterized in that: The medium stores a program, which can be executed by a processor to implement the method according to any one of claims 1 to 12.

Images