Illumination system, illumination method and defect detection equipment

Abstract

The invention relates to the technical field of semiconductor front channel detection, discloses a dark field detection system and method, and particularly relates to a detection system, a detection method, defect detection equipment and a defect detection method. In the technical scheme provided by the embodiment of the invention, a plurality of illumination modules and corresponding sensor assemblies are arranged, each illumination module can generate detection light beams in different states, each sensor assembly is provided with a plurality of sensors, and each sensor can acquire scattered light signals in different states. By combining the modules and the components, scattered light signals of different defect types can be collected in a one-time scanning process, the classification precision is directly improved, and the defect type detection range is expanded by providing multi-dimensional signals.

Description

Technical Field

[0001] The present application relates to the field of semiconductor front-end inspection technology, and is a dark field inspection system and method, specifically a lighting system, a lighting method and a defect inspection device. Background Art

[0002] Wafers are the substrate of chips. If there are defects on the surface of the wafer, the prepared chips will fail, which will reduce the yield of the chips and increase the manufacturing cost. Therefore, a common method is to perform wafer surface defect detection before or during chip preparation. Wafer surface defect detection refers to detecting whether there are defects such as grooves, particles, scratches, etc. on the surface of the wafer and the location of the defects.

[0003] At present, the commonly used optical detection method for defect detection is the light scattering method, and its basic principle is to determine the presence and size of defects by scanning and detecting the presence of incident light and the scattered light of defects and the intensity of the scattered light of defects. In particular, the lighting system usually sets the incident light to vertical incidence and oblique incidence, and the detection equipment is set to small-angle reception and large-angle reception, with a total of 4 detection channels. Usually, due to assembly errors, the vertical light spot and the inclined light spot cannot overlap or are inconsistent in size, resulting in inconsistent light intensity distribution at the same detection position, affecting the reliability of the defect detection results. In practice, due to the imprecise and unquantified adjustment of the lighting system, the vertical light spot and the inclined light spot do not strictly overlap or are consistent in size or the light intensity distribution is inconsistent, thus affecting the accuracy of detection. Summary of the invention

[0004] In order to address the technical gaps in the prior art, the embodiments of the present application provide a lighting system, a lighting method and a defect detection device, which can determine whether the current scanning spot meets the target requirements and adjust the incident light path to improve the accuracy of the detection results.

[0005] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, a lighting system is provided, the system comprising: a light source for generating an incident light beam; a beam shaping device for adjusting the angle of the incident light beam based on an illumination target so that the incident light beam forms an incident light spot on the surface of an illuminated object at a target angle; the incident light spot is scattered by the surface of the illuminated object to form a scattered light beam, and the scattered light beam is received by a detector through a collection channel; a sensor component can be optionally arranged on the scattered light beam path, and can be used to receive the scattered light beam and perform imaging to obtain a real-time light spot image including the incident light spot; a processor determines whether the incident light beam deviates from the target angle and whether the incident light spot meets the target size according to the real-time light spot image, and determines an adjustment offset, and sends the adjustment offset to the beam shaping device.

[0007] In another practicable manner, the incident light beam is split into a first incident light beam and a second incident light beam by the beam shaping device, and the first incident light beam and the second incident light beam have different incident angles relative to the object to be illuminated.

[0008] In another practicable manner, two scattered light collecting devices with different collection angles are arranged on the scattered light beam path for collecting scattered light beams in different scattering angle ranges; and two collection channels are matched with the scattered light collecting devices.

[0009] In another practicable manner, the sensor component may be selectively disposed on a first path where the scattered light beam does not enter the scattered light collecting device.

[0010] In another practicable manner, the sensor component may be selectively disposed in any one of two different acquisition channels.

[0011] In another practicable manner, the sensor assembly includes at least one reflector and a sensor.

[0012] In another practicable manner, the sensor assembly further includes a telecentric lens.

[0013] In another practicable manner, the beam shaping device includes a reflector and a shaping lens group arranged on the first incident light beam propagation path and the second incident light beam propagation path, and the reflector and the shaping lens group are respectively used to make the first incident light beam and the second incident light beam incident at a target angle and a target size.

[0014] In another practicable manner, the processor is used to control the reflection angle of the reflector so that the first incident light beam and the second incident light beam are incident at a target angle, and the processor is used to control the focal length of the shaping lens group so that the first incident light beam and the second incident light beam are incident at a target size.

[0015] In a second aspect, a lighting method is provided, which is applied to the processor described in any one of the above items, and the method includes: acquiring the center coordinates and the long side size of the real-time spot image; comparing the center coordinates and the long side size with the standard center coordinates and the standard long side size to determine the center offset and the size offset; and determining the adjustment amount of the beam shaping device based on the center offset and the size offset based on the adjustment mapping relationship, and controlling the beam shaping device to adjust based on the adjustment amount of the beam shaping device.

[0016] In another practicable manner, obtaining the center coordinates of the real-time spot image and the long side size includes: extracting effective pixels of the real-time spot image based on a threshold, and obtaining the first boundary and the second boundary corresponding to the first pixel direction and the second pixel direction respectively; the first pixel direction is the X direction of the spot, and the second pixel direction is the Y direction of the spot; determining the grayscale value of the real-time spot image, and determining the center coordinates of the image based on the first boundary and the second boundary through Gaussian fitting; determining the long side size based on the first boundary and the second boundary in the first pixel direction.

[0017] In another practicable manner, the method further includes: respectively obtaining the center coordinates and long side dimensions of a first light spot and a second light spot corresponding to the first incident light beam and the second incident light beam, and determining the offset of the center coordinates and the long side dimensions of the first light spot and the second light spot, and adjusting the beam shaping device corresponding to the first incident light beam and / or the second incident light beam based on the offset until the center coordinates and the long side dimensions of the first light spot and the second light spot coincide.

[0018] In another practicable manner, the center offset and the size offset are used to determine the adjustment amount of the beam shaping device based on the adjustment mapping relationship, including: using the center offset to determine the adjustment amount of the reflector based on the angle adjustment mapping relationship, and using the size offset to determine the focal length adjustment amount of the shaping lens group based on the size adjustment mapping relationship; and controlling the beam shaping device to adjust based on the beam shaping device adjustment amount, including: adjusting the reflector based on the reflector adjustment amount, and adjusting the focal length of the shaping lens group based on the focal length adjustment amount.

[0019] In a third aspect, a defect detection device is provided, comprising: a carrier for placing an object to be detected and moving it along an equidistant spiral line; an illumination system as described in any of the above items, for generating an incident light beam that meets a target angle and a target size to the object to be detected, and generating a scattered light beam through the object to be detected; a detector assembly, for receiving the scattered light beam and generating a scattered light signal; and a processing center, for processing the scattered light signal to obtain a detection result.

[0020] The embodiments of the present invention bring the following beneficial effects:

[0021] In the technical solution provided in the embodiment of the present application, by setting a sensor component capable of monitoring the scanning light spot in the lighting system, the monitoring and correction of the incident light beam are achieved, so that the incident light beam can form a detection light spot that meets the requirements on the surface of the object to be detected; and the sensor component is selectively set to avoid interference with the reception of the detection signal.

[0022] Other features and advantages of the present disclosure will be set forth in the following description, or some features and advantages may be inferred or unambiguously determined from the description, or may be learned by implementing the above-mentioned technology of the present disclosure.

[0023] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments 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 creative work.

[0025] The methods, systems and / or programs in the accompanying drawings will be further described according to exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. These exemplary embodiments are non-limiting exemplary embodiments, wherein example numbers represent similar mechanisms in the various views of the accompanying drawings.

[0026] Figure 1 is a schematic diagram of the lighting device structure;

[0027] Figure 2 It is a schematic diagram of the structure of the sensor component;

[0028] Figure 3 A schematic diagram of the structure of a detection system in an embodiment;

[0029] Figure 4 A schematic diagram of the structure of a detection system in another embodiment;

[0030] Figure 5 A schematic diagram of the structure of a detection system in another embodiment;

[0031] Figure 6 Schematic diagram of the scanning process;

[0032] Figure 7 A schematic diagram of a detection method flow chart;

[0033] Figure 8 A schematic diagram of the structure of a defect detection device provided in an embodiment of the present application;

[0034] Fig. 9 A schematic diagram of a defect detection method flow chart provided in an embodiment of the present application.

[0035] Fig.10 A schematic diagram of the adjustment relationship provided in the embodiment of the present application;

[0036] Fig.11 A schematic diagram of the readable medium structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] In order to better understand the above technical scheme, the technical scheme of the present application is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical scheme of the present application, rather than limitations on the technical scheme of the present application. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0038] In the following detailed description, numerous specific details are set forth by way of example in order to provide a comprehensive understanding of the relevant guidance. However, it will be apparent to those skilled in the art that the present application may be practiced without these details. In other cases, well-known methods, procedures, systems, compositions and / or circuits have been described at a relatively high level, without detail, in order to avoid unnecessarily obscuring aspects of the present application.

[0039] Flowcharts are used in the present application to illustrate the execution process performed by the system according to the embodiment of the present application. It should be clearly understood that the execution process of the flowchart may not be performed in order. On the contrary, these execution processes may be performed in reverse order or simultaneously. In addition, at least one other execution process may be added to the flowchart. One or more execution processes may be deleted from the flowchart.

[0040] The embodiment of the present application provides a dark field detection system, which is applied to dark field detection. A light spot is formed by projecting a laser of a specific wavelength onto the surface of the object to be tested, so as to detect the object to be tested. Among them, the object to be tested is a wafer to be tested. Among them, the "wafer" in this embodiment generally refers to a substrate formed by a semiconductor or non-semiconductor material. Examples include (but are not limited to) single crystal silicon, gallium arsenide, gallium nitride, and indium phosphide. Such substrates can usually be found and / or processed in semiconductor manufacturing facilities. In some cases, a wafer may include only a substrate (i.e., a bare chip). Alternatively, a wafer may include one or more layers of different materials formed on a substrate. One or more layers formed on a wafer may be "patterned" or "unpatterned". For example, a wafer may include multiple bare chips with repeatable pattern features.

[0041] In the prior art, a light spot is generally scanned in a spiral motion on the wafer to be inspected to obtain the distribution of light signals on the complete surface of the wafer to be inspected, and then an analysis is performed based on the distribution of light signals to determine whether there are defects at each scanning position and the type of defects.

[0042] Among them, for the accuracy of the detection result, it is necessary to first determine the integrity of the scanning spot. In this embodiment, the integrity refers to the scanning position and size of the scanning spot.

[0043] For the scanning process, please refer to Figure 1 As shown. The scanning spot is formed on the surface of the wafer to be detected, and the offset of the spot position and the change of the spot size will affect the intensity of the generated scattering signal. Therefore, in order to ensure the accuracy of the detection result, it is necessary to first determine the integrity of the scanning spot. The integrity in this embodiment refers to whether the scanning position and size of the scanning spot meet the detection requirements, that is, when performing the wafer scanning detection described in the above-mentioned prior art, it is necessary to determine whether the scanning position and spot size of the scanning spot meet the requirements, and adjust the current incident light beam so that the scanning spot is shaped to the detection requirements.

[0044] Specifically, for the above background technology and final technical effects, please refer to Figure 2 The present embodiment provides an illumination system 10, which is applied to wafer detection, and includes a light source 11, a beam shaping device 12, a sensor assembly 13, and a processor 14. The light source is used to provide an incident light beam 16 to a wafer 20 to be detected, and the incident light beam is a laser light beam. The beam shaping device is used to perform optical posture adjustment processing on the incident light beam, specifically, to adjust the angle of the incident light beam so that the incident light beam forms an incident light spot on the surface of the wafer to be detected at a target angle. The incident light spot, i.e., the scanning light spot, is scattered by the surface of the wafer to be detected to form a scattered light beam 17, and the scattered light beam is received by the detector 15 through the collection channel.

[0045] Among them, in this embodiment, the beam shaping device should also include a plurality of lens combinations, and the incident light beam can be adjusted through the plurality of lens combinations so that the incident light beam is in an ideal state; the adjustment includes but is not limited to optical processing means such as collimation adjustment and size adjustment.

[0046] The sensor component can be selectively arranged on the scattered light beam path, and can be used to receive the scattered light beam and perform imaging to obtain a real-time light spot image including the incident light spot.

[0047] In this embodiment, the sensor assembly is the main component for spot monitoring and spot quality evaluation, and its working logic is to image the spot and transmit the acquired real-time spot image to the processor. The processor determines whether the real-time spot image meets the detection requirements through an image processing method, and adjusts the incident light beam if it does not meet the detection requirements.

[0048] In this embodiment, the main reason for not meeting the detection requirements is that the size and the incident position of the incident light beam do not meet the requirements. Therefore, when the above detection requirements are not met, the adjustment of the incident light beam is also mainly achieved by adjusting the incident position and the size of the incident light beam. Specifically, the incident position is adjusted by determining the position of the real-time spot image in the background, and the size of the incident light beam is adjusted by determining the contour size information of the real-time spot image. The above are collectively referred to as offsets in this embodiment, so the above process can be summarized as determining the adjustment offset of the scanning spot after obtaining the offset, and sending the adjustment offset to the beam shaping device, and the beam shaping device performs optical posture adjustment processing on the incident light beam according to the offset to meet the detection requirements.

[0049] In this embodiment, because the working logic of the sensor assembly is to obtain a light spot image, the scattered light beam needs to be received by the sensor assembly, and the sensor assembly needs to be on the scattered light beam path when performing light spot monitoring; and when the sensor assembly is on the scattered light beam path, it will cause interference to the detector receiving the scattered light beam. Therefore, the sensor assembly should not be always set on the scattered light beam path.

[0050] Therefore, in order to solve this technical problem, the sensor component is selectively arranged on the scattered beam path. Specifically, the sensor component can be moved into the scattered beam path or out of the scattered beam path according to the needs of spot monitoring in the entire system. Figure 2 The arrow direction is the direction in which the sensor assembly is removed.

[0051] Moreover, the incident angle and size of the scanning spot do not need to be adjusted in real time in actual scenarios. Generally, the incident angle and size are adjusted at the beginning of the detection task. In other scenarios, a monitoring task can be set at any node in the detection process for secondary monitoring and adjustment. It can be set according to specific detection tasks and detection requirements. It will not be repeated in this embodiment. This embodiment is only used to illustrate how to monitor and how to adjust.

[0052] In summary, this embodiment realizes the monitoring of the incident light beam through the above-mentioned components, so that the scanning spot of the incident light beam determines whether there is a problem that the incident position and the spot size do not meet the detection requirements through image processing means, and adjusts the beam shaping device according to the offset until the scanning position and spot size of the spot meet the detection requirements.

[0053] In this embodiment, how to implement the adjustment and the adjustment process are described in detail. Figure 3The schematic diagram of the lighting system structure shown in the figure shows that the beam shaping device in this embodiment includes a reflector 121 and a shaping lens group arranged along the propagation path of the incident light beam, wherein the reflector is used to make the incident light beam incident on the surface of the wafer to be detected at a target angle, and the shaping lens group includes at least two cylindrical lenses 122 for changing the focal length of the incident light beam and other shaping, wherein other shaping includes but is not limited to optical processing means such as aberration control. Among them, the incident position deviation presented by the scanning light spot is based on the deviation of the incident angle of the incident light beam, and the size deviation of the incident light beam is based on the deviation of the focal length of the incident light beam. Therefore, in this embodiment, in order to solve the problem that the scanning light spot does not meet the detection requirements, it is necessary to change the incident angle of the incident light beam and the focal length of the incident light beam.

[0054] The incident angle of the incident light beam is determined by the reflector, and the focal length of the incident light beam is determined by the relative position relationship of the cylindrical lenses. Therefore, in this embodiment, in order to solve the problem that the scanning spot does not meet the detection requirements, it is achieved by adjusting the reflection angle of the reflector in the beam shaping device and adjusting the focal length of the incident light beam. The reflection angle adjustment of the reflector is determined by the offset, and the reflection angle adjustment amount is compensated by the reflection angle adjustment amount; the focal length of the incident light beam is achieved by adjusting the spatial position relationship of at least two cylindrical lenses in the shaping lens group, that is, by adjusting the spatial position relationship of at least two cylindrical lenses, the focal length of the incident light beam is adjusted, so that the size of the scanning spot is changed. The spatial relationship in this embodiment refers to the air gap between at least two cylindrical lenses along the optical axis, and the adjustment of the cylindrical lenses is achieved by adjusting the distance of the air gap.

[0055] Among them, see Fig.10 It can be seen from the adjustment relationship and size change relationship of the cylindrical lens shown that the adjustment range of the air gap between the cylindrical lenses in this embodiment is 1mm-12mm, and the corresponding change in the long side size of the scanning spot is 50um-380um. This corresponding relationship is a standard corresponding relationship. The corresponding air gap adjustment range can be determined by determining the change in the long side size. In addition, according to the characteristics of the scanning spot, there is a corresponding relationship between the long side and the short side of the scanning spot. By adjusting the long side of the scanning spot, the short side of the spot can be adjusted synchronously to determine the overall size of the corresponding scanning spot. Therefore, in this embodiment, only the long side of the scanning spot can be used as the adjustment object.

[0056] In this embodiment, the position deviation of the scanning spot formed by the incident light beam on the wafer to be inspected is adjusted by adjusting the reflection angle of the reflector in the beam shaping device, and the size of the scanning spot is adjusted by adjusting the air gap along the optical axis of at least two cylindrical lenses in the shaping lens group.

[0057] As for how to determine whether the scanning light spot has position deviation and size deviation, this embodiment implements it through an image processing method. Specifically, the scanning light spot is imaged by a sensor component arranged on the scattered light beam path to obtain a real-time light spot image, and the real-time light spot image is processed by a processor to obtain whether there is a deviation and the adjustment amount corresponding to the deviation.

[0058] The sensor assembly includes at least one reflector and a sensor, wherein the reflector is used to change the propagation path of the scattered light beam to the sensor. In this embodiment, the reflector is a scattering reflector for distinguishing. After being reflected by the scattering reflector, the scattered light beam enters the target surface of the sensor to form a real-time spot image. In this embodiment, a CCD area array camera can be selected for the sensor.

[0059] It is worth noting that the focal length relationship between the two cylindrical lenses in this embodiment should meet the following condition: 0.5<f1 / f2<1.5, where f1 and f2 represent two cylindrical lenses respectively.

[0060] The sensor transmits the acquired real-time spot image to the processor, and the processor adjusts the system by executing the following steps. For more information, please refer to Figure 4 In this embodiment, a lighting method is configured in the processor to implement the adjustment of the lighting system, which specifically includes the following steps:

[0061] Step S41: Obtain the center coordinates and long side size of the real-time spot image.

[0062] In this embodiment, to determine the above two image feature values, it is first necessary to determine the effective pixel range in the real-time spot image. Among them, if the scanning spot is a Gaussian spot that conforms to the Gaussian distribution, then according to the definition of the Gaussian spot radius, 1 / e2 determines the radius of the spot, that is, the threshold C = F max *1 / e 2 =13.5%*F max is the pixel peak grayscale, where F max is the pixel peak grayscale, according to the characteristics of the light spot Gaussian distribution, the effective pixels are extracted with the threshold C, and the first boundary m and the second boundary n corresponding to the XY direction of the effective pixels of the sensor target surface, that is, the first pixel direction and the second pixel direction of the target surface of the CCD area array camera are obtained, and the pixel resolution of the effective pixel range, that is, the region of interest, is m×n. In this embodiment, the search area is narrowed by dividing the effective pixel range, thereby improving the efficiency of image processing.

[0063] In this embodiment, the determination of the spot size can be simplified to the determination of the long side size. Through the above processing, the effective pixel range can be obtained. For the obtained effective pixel range, because the second pixel direction is the Y direction, the determination of the long side size can be directly determined by the second boundary n corresponding to the second pixel direction.

[0064] As for the center coordinate of the light spot, in this embodiment, the gray value of the real-time light spot image, that is, f(x, y), is first determined based on the first boundary and the second boundary, where x=1, 2, ..., m; y=1, 2, ..., n, and then the center coordinate of the real-time light spot image is determined by Gaussian fitting based on the first boundary and the second boundary. For the center coordinate (x c ,y c ) can be expressed as:

[0065]

[0066] Step S42: Compare the center coordinates and the long side dimensions with the standard center coordinates and the standard long side dimensions to determine the center offset and the dimension offset.

[0067] Through step S41, the quantitative index of the center coordinate and the long side size corresponding to the real-time light spot can be obtained, and then the quantitative index is compared with the preset standard center coordinate and standard long side size that meet the detection requirements, so as to determine the center coordinate offset result and the size offset result. The offset result is the center offset amount and the size offset amount.

[0068] Step S43: Determine an adjustment amount of the beam shaping device based on the adjustment mapping relationship using the center offset and the size offset, and control the beam shaping device to adjust based on the adjustment amount of the beam shaping device.

[0069] In this embodiment, as described above, the offset of the center coordinates of the light spot is caused by the deviation of the position of the scanning light spot on the wafer to be detected based on the deviation of the reflection angle of the reflector in the beam shaping device, and the offset of the light spot size is caused by the deviation of the air gap in the optical axis direction of at least two cylindrical lenses of the shaping mirror group in the beam shaping device. The above-mentioned deviations occurring in the beam shaping device are collectively referred to as device deviations, and the compensation adjustment for the deviations is the corresponding adjustment amount.

[0070] Therefore, the center offset and size offset obtained in step S42 are image offset representation quantities, and it is necessary to convert the image offset representation quantities into device adjustment quantities, and then compensate and correct the above-mentioned device based on the device adjustment quantities.

[0071] The determination of the device adjustment amount is implemented based on building a mapping relationship.

[0072] Specifically, in this embodiment, there are angle adjustment mapping relationships and size adjustment mapping relationships. Among them, the angle adjustment mapping relationship is the correspondence between the center offset and the adjustment angle of the reflector. Through this mapping relationship, the adjustment angle of the reflection angle can be determined by the center offset obtained in step S42. Correspondingly, the size adjustment mapping relationship is the adjustment relationship between the size offset and the focal length adjustment amount. Since the focal length is determined by the air gap between at least two cylindrical lenses along the optical axis, the size adjustment mapping relationship is actually the correspondence between the size offset and the air gap adjustment amount of at least two cylindrical lenses.

[0073] Through the above two mapping relationships, this embodiment can directly map the image representation quantity obtained in step S42 into the physical adjustment quantity corresponding to the light beam adjustment device, and send the above two adjustment quantities to the corresponding device to achieve the adjustment of the spot position and spot size.

[0074] It is worth noting that the beam shaping device includes not only the corresponding optical device, but also the mechanical structure matched therewith, wherein how the beam shaping device realizes physical adjustment is realized through its corresponding mechanical structure; for example, if the shaping lens group is a barrel lens, it not only includes at least two cylindrical lenses but also a motor that drives the cylindrical lenses to move in the barrel, so the focal length adjustment of the shaping lens group is driven by the motor to move at least one cylindrical lens. Therefore, how the beam shaping device realizes physical adjustment in this embodiment is not further described or limited in this embodiment, and any solution that satisfies the above adjustment process belongs to the protection scope of this embodiment.

[0075] As can be seen from the above, a lighting system is provided for the present embodiment, which is used in wafer inspection scenarios. By configuring a sensor component, an incident light spot image formed by an incident light beam on the wafer to be inspected can be obtained, and the light spot image is processed by a processor to obtain the center position and size data of the light spot to determine whether the incident light beam meets the inspection requirements, thereby reducing the problem of inaccurate inspection results caused by unqualified incident light beams.

[0076] For the above-mentioned implementation, another implementation is also provided in this embodiment, which is also applied to wafer dark field detection. Generally, in wafer dark field detection, the incident light beam includes two incident light beams with different incident angles; specifically, one incident light beam is a normal incident light beam, and its incident angle is perpendicular to the wafer surface, and the other incident light beam is an oblique incident light beam, and its incident angle is 70° with the wafer to be detected. In addition, the oblique incident light beam and the normal incident light beam have different polarization states, specifically, the polarization state of the oblique incident light beam is P light, and the polarization state of the normal incident light beam is S light.

[0077] So, participate Figure 5 , for the above scenario, this embodiment also provides an implementation method for monitoring and adjusting the scanning spot formed by the above two incident light beams. Its basic structure is the same as the lighting system structure in the above embodiment, but the difference is that the reflector and shaping mirror group in the beam shaping device in this embodiment include two groups, respectively, which are respectively arranged in the first incident light beam and the second incident light beam. In addition, in order to achieve splitting and beam splitting, in addition to the reflector and the shaping mirror group, the beam shaping device in this embodiment also includes a polarization beam splitter 123, which is used to separate the light beams with different polarization states in the incident light beam generated by the light source into a first incident light beam 111 and a second incident light beam 112. The first incident light beam is formed into an incident light beam at an angle of 70° with the surface of the wafer to be detected by the reflector arranged on its light propagation path, and the second incident light beam is formed into an incident light beam perpendicular to the surface of the wafer to be detected by the reflector arranged on its light propagation path.

[0078] In this embodiment, the polarization state of the detection beam is continuously changed in one scanning process to generate the first incident beam and the second incident beam, so as to realize the two scattered light signal distribution states, or the two scattered light signal distribution states under different polarization states are obtained by two scanning processes, and the defect judgment is performed on the wafer to be inspected based on the two scattered light signal distribution states. In order to ensure that the scattered light signal distribution collected by the two incident beams is the same scanning collection point on the surface of the wafer to be inspected, the first light spot and the second light spot corresponding to the first incident beam and the second incident beam should have the same center coordinates and spot size.

[0079] Therefore, in this embodiment, the lighting system can monitor the two light spots, respectively obtain the center coordinates and sizes of the two light spots, and determine whether there is a deviation between the center coordinates and sizes of the two light spots. After determining the deviation value, the corresponding beam shaping device is adjusted according to the deviation value.

[0080] In this embodiment, the center coordinates and the long side sizes of the two light spots are implemented as in the above embodiment, except that the comparison object in this embodiment is the comparison between the two light spots. The center coordinates and the size of any one light spot are used as the standard reference object to compare whether the center coordinates and the size of the other light spot have deviations from the light spot and the corresponding deviation value, and the beam shaping device corresponding to the other light spot is adjusted based on the deviation value until there is no deviation between the center coordinates and the size of the two light spots.

[0081] Through the above process adjustment, the light spots formed by the first incident light beam and the second incident light beam on the surface of the wafer to be inspected can be overlapped, thereby reducing the problem of inaccurate inspection results caused by the deviation between the two.

[0082] In summary, this embodiment provides a method for adjusting corresponding light spots in a scene where two incident light beams are generated, by obtaining the central coordinates and long side dimensions of the first light spot and the second light spot, comparing the deviation between the two, and calculating the corresponding deviation value, and adjusting the corresponding beam shaping device based on the deviation value.

[0083] See also Figure 6 In other possible implementations of this embodiment, a defect detection device 100 is provided, in which a carrier, a detector assembly, a processing center and an illumination system in any of the above two implementations are provided. The carrier is used to carry the wafer to be detected and move along an equidistant spiral line so that the wafer to be detected moves with it, the detector assembly is used to receive the incident light beam generated by the illumination system and the scattered light beam generated by the wafer to be detected and generate a scattered light signal, and the processing center is used to process the scattered light signal to obtain a detection result.

[0084] In this embodiment, the preferred lighting system is a dual incident beam system, that is, the incident beam in the defect detection equipment includes a first incident beam and a second incident beam, which respectively form corresponding first light spots and second light spots on the surface of the wafer to be detected.

[0085] Among them, the detector assembly includes two detection channels, namely a large-angle detection channel and a small-angle detection channel. A detector is provided in each channel for collecting the corresponding scattered light signals. The difference between the large-angle detection channel and the small-angle detection channel is that the two collect scattered signals of different scattering angles. Specifically, the large-angle detection channel is used to obtain the scattered light signal of Bigfoot, and the small-angle detection channel is used to obtain the small-angle scattered light signal. Among them, the angle range of the large-angle scattered signal is 27-78°, and the angle range of the small-angle scattered signal is 5-25°.

[0086] The acquisition of scattered signals by the large-angle detection channel and the small-angle detection channel is realized by corresponding collecting mirrors. Specifically, corresponding collecting mirrors 33 are respectively arranged on the large-angle detection channel and the small-angle detection channel to collect the large-angle scattered light beam 31 and the small-angle scattered light beam 32, and the scattered light beams are optimized by optical devices and then enter the corresponding detectors 34.

[0087] In this embodiment, the detector used for collecting the scattered light beam is a PMT detector.

[0088] In this embodiment, the sensor component in the lighting system can be optionally set on the scattered light beam path, wherein the optional means that when the spot monitoring is performed, it enters the scattered light beam path and obtains the spot image by imaging, and when the spot monitoring is not performed, it moves out of the scattered light beam path to avoid interference with the reception of the scattered light signal.

[0089] Among them, the scattered light beam path includes three paths, namely the first path, the second path and the third path, and the above three paths are divided according to the detection channel. Among them, the second path and the third path are the paths corresponding to the large-angle detection channel and the small-angle detection channel respectively. The first path is the scattered light path that has not entered the detection channel, that is, the first incident light beam and the second incident light beam are scattered by the surface of the wafer to be detected to form a scattered light beam, but this light beam has not yet entered the above two collecting mirrors.

[0090] The sensor assembly can be selectively set in any of the three paths mentioned above, see Figure 7 The defect detection device provided is an implementation method in which the sensor assembly is arranged on the first path. In this implementation method, the sensor assembly is arranged between the reflectors corresponding to the second incident light beam, i.e., the normal incident light beam, to reflect the scattered light beam to the area array camera, wherein the area array camera is provided with a telecentric lens to obtain the spot image corresponding to the scattered light beam.

[0091] In another possible implementation, the defect detection device is an implementation in which the sensor assembly is arranged on the second path. In this implementation, the sensor assembly is arranged on a large-angle detection channel, and a reflector is arranged to reflect the scattered light beam on the detection channel to the area array camera, wherein the area array camera is provided with a telecentric lens to obtain the spot image corresponding to the scattered light beam. In other implementations, the detector can be directly replaced with the area array camera when imaging, that is, the scattered light beam originally entering the detector directly enters the area array camera to achieve spot imaging. In this embodiment, the second implementation is preferred.

[0092] For the implementation method set on the third path, please refer to Figure 8 In the defect detection device provided, the sensor assembly is arranged on a small-angle detection channel, and a reflector is arranged to reflect the scattered light beam on the detection channel to the area array camera. Similarly, in this embodiment, the area array camera is also provided with a telecentric lens.

[0093] For the above three implementations, the best choice is the first method, that is, setting the sensor component on the first path, the second best choice is to set the sensor component on the second path, and finally the third method is to set the sensor component on the third path. For the first implementation, the problem of incomplete imaging caused by incomplete reception of scattered light beams can be avoided, and the energy of the scattered light beam obtained is the strongest. Compared with the second and third implementations, the images collected can better show the characteristics of the scanning spot; similarly, the second implementation can better image than the third implementation, and is the second best choice.

[0094] In this embodiment, any one of the three implementation modes described above can be used to monitor the incident light spot, so that the first incident light beam and the second incident light beam can be completely presented on the wafer to be inspected.

[0095] Based on the above implementation, refer to Fig. 9 In this embodiment, a defect detection method is also provided to implement scanning detection of the surface of a wafer to be detected, which specifically includes the following steps:

[0096] Step S91. Determine through the lighting system whether the light spots corresponding to the first incident light beam and the second incident light beam meet the detection requirements and adjust the first incident light beam and the second incident light beam that do not meet the detection requirements.

[0097] Step S92: Use the adjusted second incident light beam and the first incident light beam to irradiate the wafer respectively, and control the stage to move in an equidistant spiral until the second incident light beam scans the entire wafer.

[0098] Step S93. Acquire large-angle scattering signals and small-angle scattering signals through the large-angle detection channel and the small-angle detection channel, and acquire the physical information DNN, WNN, DNO and WNO of the entire wafer through the processing center.

[0099] Step S94: Combine the above physical information in pairs to determine the type, location and size of defects in the entire wafer.

[0100] The lighting system, lighting method and defect detection equipment provided in the embodiments of the present application realize monitoring and correction of the incident light beam by setting a sensor component capable of monitoring the scanning light spot in the lighting system, so that the incident light beam can form a detection light spot that meets the requirements on the surface of the object to be detected; and the sensor component is selectively set to avoid interference with the reception of the detection signal.

[0101] See also Fig.11The embodiment of the present invention further provides a readable medium 11, which stores computer-readable instructions 111. The computer-readable instructions 111 include instructions for executing the aforementioned lighting method and defect detection method.

[0102] The functions and technical effects of the readable medium 11 provided in the embodiment of the present invention may refer to the technical effects of the calibration method in the aforementioned embodiment, and will not be described in detail here.

[0103] It should be noted that in the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and / or methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units / modules is only a logical function division. There may be other division methods in actual implementation, such as multiple units or modules can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0104] The units / modules described as separate components may or may not be physically separated, and the components shown as units / modules may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units / modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0105] In addition, each functional unit / module in each embodiment of the present invention may be integrated into one processing unit / module, or each unit / module may exist physically separately, or two or more units / modules may be integrated into one unit / module. The above-mentioned integrated unit / module may be implemented in the form of hardware or in the form of hardware plus software functional units / modules.

[0106] The above-mentioned integrated unit / module implemented in the form of a software functional unit / module can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for causing one or more processors of a computer device (which can be a personal computer, a server, or a network device, etc.) to perform some steps of the method described in each embodiment of the present invention.

[0107] The above-mentioned integrated unit / module implemented in the form of a software functional unit / module can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for causing one or more processors of a computer device (which can be a personal computer, a server, or a network device, etc.) to perform some steps of the method described in each embodiment of the present invention.

[0108] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 invention.

Claims

1. A lighting system, characterized in that: The system comprises: a light source for generating an incident light beam; A beam shaping device adjusts the angle of the incident light beam based on the illumination target, so that the incident light beam forms an incident light spot on the surface of the illuminated object at the target angle; the incident light spot is scattered by the surface of the illuminated object to form a scattered light beam, and the scattered light beam is received by the detector through the collection channel; A sensor assembly, which can be optionally arranged on the path of the scattered light beam, can be used to receive the scattered light beam and perform imaging to obtain a real-time light spot image including the incident light spot; The processor determines whether the incident light beam deviates from the target angle and whether the incident light spot meets the target size according to the real-time light spot image, determines an adjustment offset, and sends the adjustment offset to the beam shaping device.

2. The lighting system according to claim 1, characterized in that The incident light beam is split into a first incident light beam and a second incident light beam by the beam shaping device, and the first incident light beam and the second incident light beam have different incident angles relative to the object to be illuminated.

3. The lighting system according to claim 2, characterized in that Two scattered light collecting devices with different collection angles are arranged on the scattered light beam path, so as to collect scattered light beams in different scattering angle ranges; and two collection channels are matched with the scattered light collecting devices.

4. The lighting system according to claim 3, characterized in that The sensor assembly can be selectively arranged on a first path where the scattered light beam does not enter the scattered light collecting device.

5. The lighting system according to claim 3, characterized in that: The sensor component can be selectively arranged in any one of two different collection channels.

6. The lighting system according to claim 4 or 5, characterized in that: The sensor assembly includes at least one reflector and a sensor.

7. The lighting system according to claim 6, characterized in that The sensor assembly also includes a telecentric lens.

8. The lighting system according to claim 6, characterized in that The beam shaping device includes a reflector and a shaping mirror group arranged on the first incident light beam propagation path and the second incident light beam propagation path, and the reflector and the shaping mirror group are respectively used to make the first incident light beam and the second incident light beam incident at a target angle and a target size.

9. The lighting system according to claim 8, characterized in that The processor is used to control the reflection angle of the reflector so that the first incident light beam and the second incident light beam are incident at a target angle, and the processor is used to control the focal length of the shaping lens group so that the first incident light beam and the second incident light beam are incident at a target size.

10. A lighting method, characterized in that: The method is applied to the processor according to any one of claims 1 to 9, and the method comprises: Get the center coordinates and long side size of the real-time spot image; Compare the center coordinates and the long side dimensions with the standard center coordinates and the standard long side dimensions to determine the center offset and the dimension offset; The center offset and the size offset are used to determine an adjustment amount of the beam shaping device based on an adjustment mapping relationship, and the beam shaping device is controlled to perform adjustment based on the adjustment amount of the beam shaping device.

11. The lighting method according to claim 10, characterized in that: The acquiring of the center coordinates of the real-time spot image and the long side size comprises: Extracting effective pixels of the real-time spot image based on a threshold, and respectively obtaining a first boundary and a second boundary corresponding to a first pixel direction and a second pixel direction; the first pixel direction is an X direction of the spot, and the second pixel direction is a Y direction of the spot; Determine the grayscale value of the real-time spot image, and determine the center coordinates of the real-time spot image through Gaussian fitting based on the first boundary and the second boundary; The long side size is determined based on the first boundary and the second boundary in the second pixel direction.

12. The lighting method according to claim 10, characterized in that: The method also includes: respectively obtaining the center coordinates and long side sizes of a first light spot and a second light spot corresponding to the first incident light beam and the second incident light beam, and determining the offset of the center coordinates and the long side sizes of the first light spot and the second light spot, and adjusting the beam shaping device corresponding to the first incident light beam and / or the second incident light beam based on the offset until the center coordinates and the long side sizes of the first light spot and the second light spot coincide.

13. The lighting method according to claim 10, characterized in that: The adjustment amount of the beam shaping device is determined based on the adjustment mapping relationship of the center offset and the size offset, including: determining the adjustment amount of the reflector based on the angle adjustment mapping relationship of the center offset, and determining the focal length adjustment amount of the shaping mirror group based on the size offset. The beam shaping device is controlled to be adjusted based on the adjustment amount of the beam shaping device, including: adjusting the reflector based on the reflector adjustment amount, and adjusting the focal length of the shaping mirror group based on the focal length adjustment amount.

14. A defect detection device, characterized in that: include: The stage is used to place the object to be tested and move it along an equidistant spiral line; The lighting system according to any one of claims 1 to 9, used to generate an incident light beam that meets a target angle and a target size toward the object to be detected, and to generate a scattered light beam through the object to be detected; A detector assembly, used for receiving the scattered light beam and generating a scattered light signal; The processing center is used to process the scattered light signal to obtain the detection result.

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