Optical detection method

Abstract

An optical detection method. A substrate (100) is placed at a predetermined position of a workpiece table (200); first, an optical detection module (300) is made to photograph, one by one, at least some patterns to be subjected to detection (101) which are within a detection area (102) of the optical detection module (300); then, the workpiece table (200) rotates the substrate (100) by a predetermined angle, such that patterns to be subjected to detection (101) which are outside the detection area (102) enter the detection area (102); and in this case, the optical detection module (300) photographs, one by one, the remaining patterns to be subjected to detection (101). Therefore, there is no requirement to increase a translation motion stroke of the workpiece table (200) and the motion precision at a distal stroke position, and there is also no requirement to adjust the frame structure and overall layout of a whole machine, thereby reducing the cost and occupied area of the whole machine, and improving the process adaptability.

Description

Optical detection methods Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an optical detection method. Background Art

[0002] In the semiconductor manufacturing process, it is often necessary to use an optical-mechanical system to take pictures of the substrate adsorbed on the workpiece stage, so as to perform optical inspection processes such as defect detection and alignment detection. At this time, the workpiece stage needs to be moved to align the corresponding area of ​​the substrate with the lens of the optical-mechanical system.

[0003] When the optical detection module of the optical-mechanical system is located at the center of the workpiece stage, the detection area of ​​the optical detection module can usually cover the entire substrate within the travel range of the workpiece stage. However, since important optical elements such as illumination light sources, large-aperture special lenses, etc. usually need to be set at the center or other positions of the initial position of the workpiece stage, the position of the optical detection module deviates horizontally from the center of the initial position of the workpiece stage, or the translational motion travel of the workpiece stage is asymmetric. At this time, the detection area of ​​the optical detection module cannot cover the entire substrate. In order to make the detection area of ​​the optical detection module cover the entire substrate, the translational motion travel of the workpiece stage and the motion accuracy at the long-travel position can only be forcibly increased, or the frame structure and overall layout of the whole machine can be adjusted, which ultimately increases the cost and floor space of the whole machine.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide an optical detection method for solving the problem that existing optical detection requires the use of an optical-mechanical system that is relatively costly and occupies a large area.

[0006] In order to achieve the above object, the present invention provides an optical detection method, comprising:

[0007] Providing a substrate having a plurality of patterns to be detected;

[0008] placing the substrate at a predetermined position on a workpiece stage;

[0009] Providing an optical detection module, the optical detection module is used to photograph the pattern to be detected, part of the pattern to be detected is located outside the detection area of ​​the optical detection module, and the detection area is defined by the translational motion range of the workpiece stage;

[0010] The optical detection module photographs at least a portion of the pattern to be detected within the detection area. After the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs the remaining pattern to be detected.

[0011] Optionally, the optical detection module photographs all the patterns to be detected in the detection area one by one, and after the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs the remaining patterns to be detected one by one.

[0012] Optionally, the substrate is divided into a first area and a second area in half, the first area is located in the detection area, and the optical detection module photographs all the patterns to be detected in the first area one by one. After the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs all the patterns to be detected in the second area one by one.

[0013] Optionally, the predetermined angle is 180 degrees.

[0014] Optionally, after placing the substrate at a predetermined position on the workpiece stage, the optical detection method further includes:

[0015] acquiring a position conversion relationship between the substrate and the workpiece stage; and,

[0016] The theoretical position of the workpiece stage when each of the patterns to be detected is aligned with the optical detection module is obtained by using the positions of the patterns to be detected on the substrate and the position conversion relationship.

[0017] Optionally, the theoretical position of the workpiece stage corresponding to each of the patterns to be detected and the translational motion stroke of the workpiece stage are used to determine whether all of the patterns to be detected are located within the detection range.

[0018] Optionally, when the optical detection module photographs at least part of the patterns to be detected in the detection area one by one, the workpiece stage moves to a corresponding theoretical position; and

[0019] After the workpiece stage rotates the base by the predetermined angle, the theoretical position of the workpiece stage corresponding to the remaining patterns to be detected and the predetermined angle are used to obtain the corrected theoretical position of the workpiece stage. When the optical detection module photographs the remaining patterns to be detected one by one, the workpiece stage moves to the corresponding corrected theoretical position.

[0020] Optionally, a first motion trajectory of the workpiece stage is planned using the theoretical position of the workpiece stage corresponding to at least part of the patterns to be detected in the detection area, and when the optical detection module photographs at least part of the patterns to be detected in the detection area one by one, the workpiece stage moves according to the first motion trajectory; and

[0021] After the workpiece stage rotates the base by the predetermined angle, a second motion trajectory of the workpiece stage is planned using the corrected theoretical position of the workpiece stage corresponding to the remaining patterns to be detected. When the optical detection module photographs the remaining patterns to be detected one by one, the workpiece stage moves according to the second motion trajectory.

[0022] Optionally, the position of the optical detection module deviates horizontally from the center of the initial position of the workpiece stage; or, the translational movement stroke of the workpiece stage is asymmetric horizontally.

[0023] Optionally, the pattern to be detected is a defect on the surface of the substrate, and the optical detection method is used to perform defect detection on the substrate; or, the pattern to be detected is an edge of the substrate, and the optical detection method is used to perform coarse alignment between the substrate and the workpiece stage.

[0024] In the optical detection method provided by the present invention, the substrate is placed at a predetermined position of the workpiece stage, and the optical detection module is first ordered to photograph at least part of the pattern to be detected within the detection area of ​​the optical detection module one by one. Then the workpiece stage rotates the substrate by a predetermined angle so that the pattern to be detected outside the detection area enters the detection area. At this time, the optical detection module photographs the remaining patterns to be detected one by one, thereby eliminating the need to increase the translational motion stroke of the workpiece stage and the motion accuracy at the long-stroke position, and eliminating the need to adjust the entire machine frame structure and overall layout, thereby reducing the cost and footprint of the entire machine and improving process adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a flow chart of an optical detection method provided in Example 1 of the present invention;

[0026] FIG2 is a schematic diagram of a substrate provided in Example 1 of the present invention;

[0027] FIG3 is a schematic diagram of a workpiece stage and an optical detection module provided in Example 1 of the present invention;

[0028] FIG4 is a schematic diagram of a detection area of ​​the optical detection module within the translational motion range of the workpiece stage provided in the first embodiment of the present invention;

[0029] FIG5 is a schematic diagram of a substrate rotated 180 degrees according to the first embodiment of the present invention;

[0030] 6 is a schematic diagram of a detection area of ​​an optical detection module within the translational motion range of a workpiece stage provided in a second embodiment of the present invention;

[0031] FIG7 is a schematic diagram of a substrate rotated 180 degrees according to a second embodiment of the present invention;

[0032] The reference numerals are: 100 - substrate; 101 - pattern to be detected; 102 - detection area; 200 - workpiece stage; 300 - optical detection module; 110 - first area; 120 - second area. DETAILED DESCRIPTION

[0033] The following is a more detailed description of the specific embodiments of the present invention with reference to schematic diagrams. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are only used for the purpose of conveniently and clearly illustrating the embodiments of the present invention.

[0034] Example 1

[0035] FIG1 is a flow chart of the optical detection method provided in this embodiment. As shown in FIG1 , the optical detection method includes:

[0036] Step S100: providing a substrate having a plurality of patterns to be detected thereon;

[0037] Step S200: placing the substrate at a predetermined position on a workpiece table;

[0038] Step S300: providing an optical detection module, wherein the optical detection module is used to photograph the pattern to be detected, wherein a portion of the pattern to be detected is located outside a detection area of ​​the optical detection module, and the detection area is defined by the translational motion range of the workpiece stage; and

[0039] Step S400: the optical detection module photographs at least a portion of the pattern to be detected in the detection area. After the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs the remaining pattern to be detected.

[0040] 2 to 5 are schematic structural diagrams corresponding to the corresponding steps of the optical detection method provided by this embodiment. Next, the optical detection method provided by this embodiment will be described in detail with reference to FIG2 to 5.

[0041] Figure 2 is a schematic diagram of the substrate 100 provided in this embodiment. As shown in Figure 2, step S100 is performed to provide a substrate 100. The substrate 100 can be a substrate commonly used in the semiconductor field, such as a wafer or a mask. The substrate 100 can be circular or square, and the present invention does not limit this.

[0042] The substrate 100 has a plurality of patterns 101 to be inspected. In this embodiment, the patterns 101 to be inspected are defects on the substrate 100, and the optical inspection method is used to perform defect inspection on the substrate 100. In this embodiment, the positions of the patterns 101 to be inspected on the substrate 100 are known. For example, the positions of the patterns 101 to be inspected on the substrate 100 may be the positions of the centers of the defects on the substrate 100.

[0043] In some embodiments, the pattern to be detected 101 may also be the edge of the substrate 100. In this case, the optical detection method is used to detect the edge of the substrate 100, thereby achieving coarse alignment between the substrate 100 and the workpiece stage. In this case, the position of the pattern to be detected 101 on the substrate 100 can be the vertex of the edge or the positions of several sampling points of the edge on the substrate 100.

[0044] It should be understood that, for ease of understanding, FIG2 schematically uses a circle to represent the pattern to be detected 101 , but in fact, the pattern to be detected 101 is not limited to a circle, but can also be any regular or irregular shape, or even a point.

[0045] Figure 3 is a schematic diagram of the workpiece stage 200 and optical inspection module 300 provided in this embodiment. As shown in Figure 3 , during steps S200 and S300 , a robot removes the substrate 100 from the cassette and transfers it to the workpiece stage 200 . The robot then places the substrate 100 at a predetermined position on the workpiece stage 200 (typically, the center of the workpiece stage 200 ). The optical inspection module 300 is located above the workpiece stage 200 and is used to image the pattern 101 to be inspected on the substrate 100 .

[0046] It is understandable that when the position of the optical inspection module 300 deviates horizontally from the center of the initial position of the workpiece stage 200, or the translational motion range of the workpiece stage 200 is asymmetric horizontally, the inspection area of ​​the optical inspection module 300 within the translational motion range of the workpiece stage 200 is very likely to be unable to cover the entire substrate 100. As shown in FIG3 , the position of the optical inspection module 300 deviates to the right (relative to the orientation in FIG3 ) from the center of the initial position of the workpiece stage 200 in the x-direction. As a result, the inspection area 102 of the optical inspection module 300 within the translational motion range of the workpiece stage 200 is very likely to be unable to cover the portion of the substrate 100 near the edge on the left side (relative to the orientation in FIG3 ).

[0047] Next, due to the possibility of loading deviation during the loading process of the robot, the position of the substrate 100 on the work stage 200 has a position deviation from the predetermined position. Based on this, the work stage 200 starts to move, so that the optical detection module 300 is aligned with the alignment mark (not shown in the figure) on the substrate 100, thereby starting to shoot the alignment mark on the substrate 100 to obtain an alignment image. By identifying the alignment image, the pixel position of the alignment mark on the alignment image can be obtained, and the position conversion relationship between the optical detection module 300 and the work stage 200 and the pixel position of the alignment mark on the alignment image can be used to obtain the position conversion relationship between the substrate 100 and the work stage 200.

[0048] Next, since the position of each of the patterns to be detected 101 on the substrate 100 is known, the position of each of the patterns to be detected 101 on the substrate 100 is converted to a theoretical position of the work stage 200 using the position conversion relationship between the substrate 100 and the work stage 200. The theoretical position of the work stage 200 is the position where the work stage 200 should be when the patterns to be detected 101 are aligned with the optical detection module 300.

[0049] Afterwards, the theoretical position of the workpiece stage 200 corresponding to each of the patterns 101 to be detected and the translational travel of the workpiece stage 200 can be used to determine whether the patterns 101 to be detected are all within the detection range. For example, with the center of the workpiece stage 200 as the origin, and the translational travel of the workpiece stage 200 in the X and Y directions being ±50, if the x-coordinate of the theoretical position of the workpiece stage 200 corresponding to the pattern 101 to be detected is greater than +50 or less than -50, or the y-coordinate of the theoretical position of the workpiece stage 200 corresponding to the pattern 101 to be detected is greater than +50 or less than -50, then it indicates that the pattern 101 to be detected is outside the detection range.

[0050] If all the patterns 101 to be detected are within the detection range, it indicates that the optical detection module 300 is able to photograph all the patterns 101 to be detected. At this time, the optical detection module 300 only needs to photograph all the patterns 101 to be detected one by one; if at least one of the patterns 101 to be detected is outside the detection range, it indicates that the optical detection module 300 is unable to photograph all the patterns 101 to be detected.

[0051] Figure 4 is a schematic diagram of the detection area 102 of the optical inspection module 300 provided in this embodiment within the translational range of the workpiece stage 200. As shown in Figure 4, in this embodiment, five of the patterns 101 to be inspected are located within the detection area 102, and two are located outside of the detection area 102. It should be understood that the relationship between the detection area 102 and the patterns 101 to be inspected in Figure 4 is merely illustrative; whether the pattern 101 to be inspected is within the detection range needs to be determined based on actual circumstances.

[0052] Please continue to refer to Figure 4 and execute step S400. Use the theoretical position of the workpiece stage 200 corresponding to the five patterns to be detected 101 in the detection area 102 to plan the first motion trajectory of the workpiece stage 200. The workpiece stage 200 moves according to the first motion trajectory, and the optical detection module 300 can photograph the five patterns to be detected 101 in the detection area 102 one by one.

[0053] Afterwards, the work stage 200 rotates the substrate 100 by a predetermined angle. In this embodiment, the predetermined angle is 180 degrees. FIG5 is a schematic diagram of the substrate 100 after being rotated 180 degrees, according to this embodiment. As shown in FIG5 , after the work stage 200 rotates the substrate 100 by 180 degrees, two to-be-detected patterns 101 that were not originally within the detection area 102 now enter the detection area 102.

[0054] Since the position of the substrate 100 changes after the substrate 100 is rotated 180 degrees, the positions of the remaining two patterns 101 to be detected also change. Therefore, it is necessary to use the theoretical positions of the workpiece stage 200 corresponding to the remaining two patterns 101 to be detected and the predetermined angle of rotation of the substrate 100 to obtain a corrected theoretical position of the workpiece stage 200. The corrected theoretical position of the workpiece stage 200 is the position where the workpiece stage 200 should be when the remaining two patterns 101 to be detected are aligned with the optical detection module 300.

[0055] Afterwards, the second motion trajectory of the workpiece stage 200 is planned using the corrected theoretical positions of the workpiece stage 200 corresponding to the remaining two patterns 101 to be detected. The workpiece stage 200 moves according to the second motion trajectory, and the optical detection module 300 can photograph the remaining two patterns 101 to be detected one by one, thereby eliminating the need to increase the translational motion stroke of the workpiece stage 200 and the motion accuracy at the long-stroke position, and eliminating the need to adjust the entire machine frame structure and overall layout, thereby reducing the cost and footprint of the entire machine and improving process adaptability.

[0056] It should be understood that rotating the substrate 100 180 degrees can ensure that all of the patterns 101 to be detected outside the detection area 102 enter the detection area 102, and subsequent image processing is also simpler. As an optional embodiment, the predetermined angle is not limited to 180 degrees. In some embodiments, after rotating the substrate 100 by other angles, the remaining patterns 101 to be detected can also enter the detection area 102. Therefore, the rotation angle of the substrate 100 can be selected according to actual conditions.

[0057] Example 2

[0058] The difference from the first embodiment is that, in this embodiment, before the substrate 100 is rotated by a predetermined angle, the optical detection module 300 only photographs a portion of the to-be-detected patterns 101 in the detection area 102 one by one.

[0059] Figure 6 is a schematic diagram of the detection area 102 of the optical inspection module 300 provided in this embodiment within the translational range of the workpiece stage 200. As shown in Figure 6, in this embodiment, five of the patterns 101 to be inspected are located within the detection area 102, and two are located outside of the detection area 102. It should be understood that the relationship between the detection area 102 and the patterns 101 to be inspected in Figure 6 is merely illustrative; whether the pattern 101 to be inspected is within the detection range needs to be determined based on actual circumstances.

[0060] Continuing with FIG6 , step S400 is performed to divide the substrate 100 into a first region 110 and a second region 120 along the y-axis. The first region 110 is located within the detection region 102, and a portion of the second region 120 is located within the detection region 102, while the remaining portion is located outside the detection region 102. The first region 110 has three patterns 101 to be detected, and the second region 120 has four patterns 101 to be detected.

[0061] It should be understood that the present invention is not limited to dividing the substrate 100 in half along the y-direction, as long as the first area 110 is located within the detection area 102 after the substrate 100 is divided in half.

[0062] Next, the first motion trajectory of the workpiece stage 200 is planned using the theoretical position of the workpiece stage 200 corresponding to the three patterns to be detected 101 in the first area 110. The workpiece stage 200 moves according to the first motion trajectory, and the optical detection module 300 can photograph the three patterns to be detected 101 in the detection area 102 one by one.

[0063] Afterwards, the work stage 200 rotates the substrate 100 180 degrees. FIG7 is a schematic diagram of the substrate 100 after being rotated 180 degrees, according to this embodiment. As shown in FIG7 , after the work stage 200 rotates the substrate 100 180 degrees, the second region 120, which was originally not within the detection area 102, also enters the detection area 102. Naturally, the four to-be-detected patterns 101 within the second region 120 also enter the detection area 102.

[0064] Since the position of the substrate 100 changes after the substrate 100 is rotated 180 degrees, the positions of the four patterns 101 to be detected in the second area 120 also change. Therefore, it is necessary to use the theoretical positions of the workpiece stage 200 corresponding to the four patterns 101 to be detected in the second area 120 and the predetermined angle (180°) of rotation of the substrate 100 to obtain a corrected theoretical position of the workpiece stage 200. The corrected theoretical position of the workpiece stage 200 is the position where the workpiece stage 200 should be located when the four patterns 101 to be detected in the second area 120 are aligned with the optical detection module 300.

[0065] Afterwards, the second motion trajectory of the workpiece stage 200 is planned using the corrected theoretical position of the workpiece stage 200 corresponding to the four patterns to be detected 101 in the second area 120. The workpiece stage 200 moves according to the second motion trajectory, and the optical detection module 300 can photograph the four patterns to be detected 101 in the second area 120 one by one, thereby eliminating the need to increase the translational motion stroke of the workpiece stage 200 and the motion accuracy at the long-stroke position, and eliminating the need to adjust the entire machine frame structure and overall layout, thereby reducing the cost and footprint of the entire machine and improving process adaptability.

[0066] In summary, in the optical detection method provided in an embodiment of the present invention, the substrate is placed at a predetermined position of the workpiece stage, and the optical detection module is first ordered to photograph at least part of the pattern to be detected within the detection area of ​​the optical detection module one by one. Then, the workpiece stage rotates the substrate by a predetermined angle so that the pattern to be detected outside the detection area enters the detection area. At this time, the optical detection module photographs the remaining patterns to be detected one by one, thereby eliminating the need to increase the translational motion stroke of the workpiece stage and the motion accuracy at the long-stroke position, and eliminating the need to adjust the frame structure and overall layout of the entire machine, thereby reducing the cost and footprint of the entire machine and improving process adaptability.

[0067] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. The systems disclosed in the embodiments are described briefly because they correspond to the methods disclosed in the embodiments. For relevant details, refer to the method description.

[0068] It should also be noted that although the present invention has been disclosed above with reference to preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or to modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

[0069] It should also be understood that, unless otherwise specified or indicated, the terms "first", "second", "third", etc. in the specification are only used to distinguish the various components, elements, steps, etc. in the specification, and are not used to indicate the logical relationship or sequential relationship between the various components, elements, steps, etc.

[0070] It should also be understood that the terms described herein are intended to describe particular embodiments only and are not intended to limit the scope of the invention. It should be noted that the singular forms "a" and "an" as used herein and in the appended claims include plural references unless the context clearly indicates otherwise. For example, a reference to "a step" or "a device" means a reference to one or more steps or devices, and may include secondary steps as well as secondary devices. All conjunctions used should be understood in their broadest sense. Also, the word "or" should be understood to have the definition of a logical "or" rather than a logical "exclusive or" unless the context clearly indicates otherwise. Furthermore, implementation of the methods and / or apparatus in embodiments of the present invention may include performing selected tasks manually, automatically, or in combination.

Claims

1. An optical detection method, characterized in that: include: Providing a substrate, wherein the substrate has a plurality of patterns to be detected; placing the substrate at a predetermined position on a workpiece stage; Providing an optical detection module, the optical detection module is used to photograph the pattern to be detected, part of the pattern to be detected is located outside the detection area of ​​the optical detection module, and the detection area is defined by the translation movement stroke of the workpiece stage; The optical detection module photographs at least a portion of the pattern to be detected in the detection area, and after the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs the remaining pattern to be detected.

2. The optical detection method according to claim 1, characterized in that: The optical detection module photographs all the patterns to be detected in the detection area one by one, and after the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs the remaining patterns to be detected one by one.

3. The optical detection method according to claim 1, characterized in that: The substrate is divided into a first area and a second area in half, the first area is located in the detection area, the optical detection module photographs all the patterns to be detected in the first area one by one, and after the workpiece stage rotates the substrate by a predetermined angle, the optical detection module photographs all the patterns to be detected in the second area one by one.

4. The optical detection method according to claim 3, characterized in that: The predetermined angle is 180 degrees.

5. The optical detection method according to any one of claims 1 to 4, characterized in that: After placing the substrate at a predetermined position on the workpiece stage, the optical detection method further comprises: acquiring a position conversion relationship between the substrate and the workpiece stage; and, By using the position of the pattern to be detected on the substrate and the position conversion relationship, the theoretical position of the workpiece stage when each pattern to be detected is aligned with the optical detection module is obtained.

6. The optical detection method according to claim 5, characterized in that: The theoretical position of the workpiece stage corresponding to each of the patterns to be detected and the translational motion stroke of the workpiece stage are used to determine whether all of the patterns to be detected are located within the detection range.

7. The optical detection method according to claim 5, characterized in that: When the optical detection module photographs at least part of the patterns to be detected in the detection area one by one, the workpiece stage moves to a corresponding theoretical position; and After the work stage rotates the base by the predetermined angle, the corrected theoretical position of the work stage is obtained by using the theoretical position of the work stage corresponding to the remaining patterns to be detected and the predetermined angle. When the optical detection module photographs the remaining patterns to be detected one by one, the work stage moves to the corresponding corrected theoretical position.

8. The optical detection method according to claim 7, characterized in that: A first motion trajectory of the workpiece stage is planned using the theoretical position of the workpiece stage corresponding to at least part of the patterns to be detected in the detection area, and when the optical detection module photographs at least part of the patterns to be detected in the detection area one by one, the workpiece stage moves according to the first motion trajectory; and After the workpiece stage rotates the substrate by the predetermined angle, a second motion trajectory of the workpiece stage is planned using the corrected theoretical position of the workpiece stage corresponding to the remaining patterns to be detected. When the optical detection module photographs the remaining patterns to be detected one by one, the workpiece stage moves along the second motion trajectory.

9. The optical detection method according to claim 1, characterized in that: The position of the optical detection module deviates horizontally from the center of the initial position of the workpiece stage; or, the translational movement stroke of the workpiece stage is asymmetric horizontally.

10. The optical detection method according to claim 1, characterized in that: The pattern to be detected is a defect on the surface of the substrate, and the optical detection method is used to perform defect detection on the substrate; or, the pattern to be detected is an edge of the substrate, and the optical detection method is used to perform coarse alignment between the substrate and the workpiece stage.

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