Wafer defect detection method and system

Abstract

The invention relates to the technical field of semiconductors, and provides a wafer defect detection method and system. The method comprises the steps that a structural program library is provided, multiple groups of second structures are arranged in the structural program library, each group of second structures comprises at least one second structure, and each second structure corresponds to a scanning program; judging whether the first structure of the wafer to be detected corresponds to a certain second structure in the structure program library or not; when it is determined that the first structure corresponds to a certain second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program of the first structure; when it is determined that the first structure does not correspond to all the second structures in the structure program library, generating a scanning program of the first structure according to the alignment mark of the first structure; and scanning defects on the surface of the first structure according to the scanning program of the first structure. When wafer defect detection is carried out by adopting the method, each station can automatically derive a detection program, so that the detection time and cost are reduced, and the detection efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a wafer defect detection method and system. Background Art

[0002] The entire process of wafer tape-out, from the initial state of the wafer to quality inspection and shipment, requires thousands of processes. Each process may introduce defects, thereby affecting the function, electrical parameters, reliability issues, etc. of the device. Therefore, defect detection of the wafer is required.

[0003] Scanning and morphological analysis of wafer defects helps to quickly analyze the source of abnormal defects, timely identify abnormal processes, reduce chip losses, shorten chip development cycles, and improve mass production yields.

[0004] At present, the method of scanning wafer defects is to establish a detection program, and then perform defect scanning and analysis according to the detection program. The existing wafer defect detection method has the following disadvantages:

[0005] (1) Time-consuming: A complete production process includes hundreds of defect detection sites, and each site needs to have a new detection program built separately, which increases the detection time and workload of each site;

[0006] (2) High cost: Engineers need to spend a lot of time and energy to complete the establishment of new testing procedures, which is time-consuming and increases costs;

[0007] (3) Low efficiency: A large number of special part inspection programs are used very rarely, but they occupy a large amount of machine production capacity and memory, affecting the machine's hourly output. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a wafer defect detection method and system.

[0009] A first aspect of the present invention provides a wafer defect detection method, comprising:

[0010] Preparing a wafer to be inspected, wherein the wafer to be inspected comprises a first structure, and an alignment mark is provided on a surface of the first structure;

[0011] Providing a structure program library, wherein the structure program library includes a plurality of groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program;

[0012] Determining whether the first structure of the wafer to be inspected corresponds to a second structure in the structure library;

[0013] When it is determined that the first structure of the wafer to be inspected corresponds to a second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program for the first structure;

[0014] When it is determined that the first structure of the wafer to be inspected does not correspond to any second structure in the structure program library, generating a scanning program for the first structure according to the alignment mark of the first structure;

[0015] The defects on the surface of the first structure are scanned according to the scanning program of the first structure.

[0016] In an embodiment of the present invention, the method also includes: when it is determined that the first structure of the wafer to be inspected does not correspond to all the second structures in the structural program library, taking the first structure as a new group of second structures, taking the scanning program corresponding to the first structure as a new group of second structures The scanning program, the new group of second structures and the new group of second structures The scanning program is added to the structural program library.

[0017] In an embodiment of the present invention, determining whether the first structure of the wafer to be inspected corresponds to a second structure in the structure library includes: determining whether the first structure of the wafer to be inspected is the same as or similar to a second structure in the structure library.

[0018] In an embodiment of the present invention, an alignment mark is provided on the surface of the second structure, and a scanning program corresponding to the second structure includes an alignment program generated according to the alignment mark of the second structure.

[0019] In an embodiment of the present invention, the alignment mark of the first structure and the alignment mark of the second structure have an outline pattern;

[0020] The contour pattern of the alignment mark of the first structure is the same as the contour pattern of the alignment mark of the second structure.

[0021] In the embodiment of the present invention, the outline pattern of the alignment mark is a centrally symmetrical pattern, a number, or a pattern with a special shape.

[0022] In an embodiment of the present invention, scanning the defects on the surface of the first structure according to the scanning program of the first structure includes:

[0023] Generate a photographing program according to the scanning program of the first structure;

[0024] Obtain defect photos of the first structure surface according to the photographing program.

[0025] Another aspect of the present invention provides a wafer defect detection system, comprising: a structure program library, a structure judgment module and a scanning module, wherein the structure program library has a plurality of groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program;

[0026] The structure judgment module is used for:

[0027] Determining whether a first structure of a wafer to be inspected corresponds to a second structure in the structure library, wherein the wafer to be inspected includes a first structure, and an alignment mark is provided on a surface of the first structure;

[0028] When it is determined that the first structure of the wafer to be inspected corresponds to a second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program for the first structure;

[0029] When it is determined that the first structure of the wafer to be inspected does not correspond to any second structure in the structure program library, generating a scanning program for the first structure according to the alignment mark of the first structure;

[0030] The scanning module is used to scan defects on the surface of the first structure according to a scanning program of the first structure.

[0031] In an embodiment of the present invention, when the structure judgment module determines that the first structure of the wafer to be inspected does not correspond to all the second structures in the structure program library, the first structure is used as a new group of second structures, and the scanning program corresponding to the first structure is used as a new group of second structures. The scanning program, the new group of second structures and the new group of second structures are added to the structure program library.

[0032] In an embodiment of the present invention, the surface of the second structure has an alignment mark, and the alignment mark of the first structure and the alignment mark of the second structure have a contour pattern;

[0033] The contour pattern of the alignment mark of the first structure is the same as the contour pattern of the alignment mark of the second structure.

[0034] The inspection machine at each site adopts the above-mentioned wafer defect inspection method. When wafer defect inspection is performed at each site, when the first structure of the wafer to be inspected corresponds to a second structure in the structural program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure. Each site can automatically derive the inspection program of the wafer to be inspected from the structural program library; when the first structure of the wafer to be inspected does not correspond to all the second structures in the structural program library, the scanning program of the first structure is generated according to the alignment mark of the first structure, that is, a new scanning program is created for a small number of special structures that cannot be matched to corresponding structures from the structural program library, and there is no need to create a new scanning program for each structure of the wafer to be inspected at each site, thereby greatly reducing the inspection time and inspection cost and improving the inspection efficiency.

[0035] Other features and advantages of the technical solution of the present invention will be described in detail in the specific implementation section below. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0037] Figure 1 is a flow chart of a wafer defect detection method provided by an embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of an alignment mark on a first structural surface of a wafer to be inspected in an embodiment of the present invention;

[0039] Figure 3 It is a block diagram of a wafer defect detection system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0041] In the description of the present invention, it should be understood that the terms "surface", "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying 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" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0042] As introduced in the background technology, in the existing wafer defect detection method, each site needs to create a new detection program separately. A large number of special part detection programs are used very rarely, but occupy a large amount of machine production capacity and memory, which is time-consuming, costly and inefficient.

[0043] In order to solve the above problems, an embodiment of the present invention provides a wafer defect detection method, which determines whether to create a new scanning program based on whether the first structure of the wafer to be detected corresponds to the second structure in the structural program library. If the first structure of the wafer to be detected corresponds to a second structure in the structural program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure of the wafer to be detected for defect scanning; if the first structure of the wafer to be detected does not correspond to all the second structures in the structural program library, the scanning program corresponding to the first structure is generated according to the alignment mark on the surface of the first structure of the wafer to be detected. When the present method is used to perform wafer defect detection at each site, each site can automatically derive the detection program of the wafer to be detected from the structural program library. For a small number of special structures that cannot be matched to the corresponding structure from the structural program library, a new scanning program needs to be created, which can greatly reduce the detection time and detection cost and improve the detection efficiency.

[0044] Figure 1 : is a flow chart of a wafer defect detection method provided by an embodiment of the present invention. Figure 1 As shown, the wafer defect detection method of this embodiment includes the following steps:

[0045] S100, preparing a wafer to be inspected, the wafer to be inspected comprising a first structure, and an alignment mark is provided on a surface of the first structure;

[0046] S200, providing a structure library, wherein the structure library includes a plurality of groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program;

[0047] S300, determining whether a first structure of the wafer to be inspected corresponds to a second structure in the structure program library;

[0048] S310, when it is determined that the first structure of the wafer to be inspected corresponds to a second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program for the first structure;

[0049] S320, when it is determined that the first structure of the wafer to be inspected does not correspond to any second structure in the structure program library, generating a scanning program for the first structure according to the alignment mark of the first structure;

[0050] S400, scanning defects on the surface of the first structure according to a scanning program of the first structure.

[0051] After the wafer to be inspected has gone through a process flow at one station, a first structure is formed on the wafer to be inspected. The first structures of each station may be the same or different. The surface material and roughness of the first structure of the wafer to be inspected at each station are different. Specifically, each process flow is determined according to the structure of the device. The process flow includes thin film deposition, thin film etching, etc. The first structure formed after the process flow may be a thin film structure, a groove structure, a boss structure, etc.

[0052] In a specific embodiment, in the above step S100, if Figure 2 As shown, an alignment mark 101 is provided on the surface of a first structure 100 of the wafer to be inspected. The alignment mark 101 is used for position alignment in a subsequent process flow or during wafer inspection.

[0053] The alignment mark of the first structure is a contour pattern, which can be a centrally symmetrical pattern, a number, or a pattern with a special shape. Figure 2 As shown, the alignment mark 101 is a centrally symmetrical figure in the shape of a cross.

[0054] In a specific embodiment, in the above step S200, there are multiple groups of second structures in the structure program library, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program. The structures of the multiple second structures in each group are the same or similar, and are structures of the same type.

[0055] The surface of the second structure is provided with an alignment mark, and the scanning program corresponding to the second structure includes an alignment program generated according to the alignment mark of the second structure. For the same or similar first structure and second structure, the alignment mark of the first structure of the wafer to be inspected is the same as the contour graphic of the alignment mark of the second structure in the structure program library, so that when the first structure of the wafer to be inspected corresponds to the second structure in the structure program library, the scanning program of the second structure can be applied to the inspection of the first junction.

[0056] The alignment mark of the second structure is a contour figure, and the contour figure can be a central symmetrical figure, a number or a figure with a special shape. Specifically, the alignment mark of the second structure is a central symmetrical figure of a "cross". The contour figure of the alignment mark of the first structure is the same as the contour figure of the alignment mark of the second structure.

[0057] The structure program library is embedded in the inspection machine at the site, and the inspection machine automatically inspects the wafer to be inspected according to the scanning program and the photo-taking program.

[0058] The information of the alignment mark on the first structure surface of each station only includes contour information, and does not include material information, roughness information, etc. of the first structure surface of each station. Therefore, the scanning programs generated based on the alignment mark can be shared, reducing the number of new scanning programs that need to be created, weakening the influence of different first structure surfaces at different stations, and increasing the accuracy of alignment; in addition, when creating a new scanning program, only the contour information of the alignment mark needs to be identified, which shortens the time for creating a new scanning program, reduces manpower and machine engineering time, saves costs and increases the machine's hourly output rate.

[0059] In a specific embodiment, in the above step S300, it is determined whether the first structure of the wafer to be inspected is the same or similar to a second structure in the structure library to determine whether the first structure corresponds to the second structure. Whether the first structure is the same or similar to the second structure can be determined by engineers based on standards or experience, or can be identified by artificial intelligence methods.

[0060] In the above step S310, if the first structure corresponds to a second structure in the structure program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure. The scanning program of the first structure includes an alignment program generated based on the alignment mark of the first structure, and the scanning program of the second structure includes an alignment program generated based on the alignment mark of the second structure. Since the contour graphics of the alignment mark of the first structure and the alignment mark of the second structure are the same, the scanning program of the second structure can be used as the scanning program of the first structure. Specifically, the scanning program of the second structure is copied, and the copied scanning program is renamed as the scanning program corresponding to the first structure. The contents of the scanning program of the first structure and the scanning program of the second structure are the same, but the names are different so as to correspond to each structure.

[0061] In the above step S320, if the first structure of the wafer to be inspected does not correspond to any of the second structures in the structure program library, the first structure is used as a new group of second structures, and a scanning program corresponding to the first structure is generated according to the alignment mark of the first structure. The scanning program corresponding to the first structure is used as a new group of second structure scanning programs, and the new group of second structures and the new group of second structure scanning programs are added to the structure program library. The first structure can also be added as a new second structure to the group corresponding to the second structure, and grouped together.

[0062] The first structure is used as a new second structure, and a scanning program is generated according to the alignment mark of the first structure. Since the alignment mark of the first structure includes a contour pattern, when a new scanning program is created according to the alignment mark of the first structure, only the contour information of the alignment mark needs to be identified, which shortens the time for creating a new scanning program, reduces manpower and machine engineering time, saves costs, and increases the machine's hourly output rate.

[0063] In a specific embodiment, in the above step S400, the defects on the surface of the first structure are scanned according to the scanning program of the first structure, specifically, a photographing program is generated according to the scanning program of the first structure, and a defect photo of the surface of the first structure is obtained according to the photographing program. The defect photo is analyzed and compared to determine the defect source of the wafer to be inspected.

[0064] The inspection machine at each site adopts the above-mentioned wafer defect inspection method. When wafer defect inspection is performed at each site, when the first structure of the wafer to be inspected corresponds to a second structure in the structural program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure. Each site can automatically derive the inspection program of the wafer to be inspected from the structural program library; when the first structure of the wafer to be inspected does not correspond to all the second structures in the structural program library, the scanning program of the first structure is generated according to the alignment mark of the first structure, that is, a new scanning program is created for a small number of special structures that cannot be matched to corresponding structures from the structural program library, and there is no need to create a new scanning program for each structure of the wafer to be inspected at each site, thereby greatly reducing the inspection time and inspection cost and improving the inspection efficiency.

[0065] Figure 3 is a block diagram of a wafer defect detection system provided by an embodiment of the present invention. Figure 3 As shown, the wafer defect detection system of this embodiment includes: a structure program library, a structure judgment module and a scanning module. The structure program library includes multiple groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program.

[0066] The structure judgment module is used to judge whether the first structure of the wafer to be detected corresponds to a second structure in the structure program library, and the wafer to be detected includes a first structure, and an alignment mark is provided on the surface of the first structure. When the structure judgment module determines that the first structure of the wafer to be detected corresponds to a second structure in the structure program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure; when it is determined that the first structure of the wafer to be detected does not correspond to all the second structures in the structure program library, the scanning program of the first structure is generated according to the alignment mark of the first structure.

[0067] When the structure judgment module determines that the first structure of the wafer to be inspected does not correspond to all the second structures in the structure program library, the first structure is used as a new group of second structures, the scanning program corresponding to the first structure is used as a new group of second structures The scanning program, the new group of second structures and the new group of second structures The scanning program is added to the structure program library.

[0068] An alignment mark is provided on the surface of the first structure of the wafer to be inspected, and the scanning program corresponding to the first structure includes an alignment program generated according to the alignment mark of the first structure. An alignment mark is provided on the surface of the second structure, and the scanning program corresponding to the second structure includes an alignment program generated according to the alignment mark of the second structure. The alignment mark of the first structure and the alignment mark of the second structure have a contour figure. The contour figure of the alignment mark of the first structure is the same as the contour figure of the alignment mark of the second structure. The contour figure of the alignment mark can be a centrally symmetrical figure, a number, or a figure with a special shape. Specifically, the alignment mark can be a centrally symmetrical figure in the shape of a "cross".

[0069] The scanning module is used to scan defects on the surface of the first structure according to the scanning program of the first structure. Specifically, a photographing program is generated according to the scanning program of the first structure, and a defect photo of the surface of the first structure is obtained according to the photographing program. The defect photo is analyzed and compared to determine the defect source of the wafer to be inspected.

[0070] The above-mentioned wafer defect detection system can be deployed on the detection machines of each site. When wafer defect detection is performed at each site, when the first structure of the wafer to be detected corresponds to a second structure in the structural program library, the scanning program corresponding to the second structure is obtained as the scanning program of the first structure. Each site can automatically derive the detection program of the wafer to be detected from the structural program library; when the first structure of the wafer to be detected does not correspond to all the second structures in the structural program library, the scanning program of the first structure is generated according to the alignment mark of the first structure, that is, a new scanning program is created for a small number of special structures that cannot be matched to corresponding structures from the structural program library, and there is no need to create a new scanning program for each structure of the wafer to be detected at each site, thereby greatly reducing the detection time and detection cost and improving the detection efficiency.

[0071] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0072] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0073] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0074] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0075] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A wafer defect detection method, characterized in that: include: Preparing a wafer to be inspected, wherein the wafer to be inspected comprises a first structure, and an alignment mark is provided on a surface of the first structure; Providing a structure program library, wherein the structure program library includes a plurality of groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program; Determining whether the first structure of the wafer to be inspected corresponds to a second structure in the structure library; When it is determined that the first structure of the wafer to be inspected corresponds to a second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program for the first structure; When it is determined that the first structure of the wafer to be inspected does not correspond to any second structure in the structure program library, generating a scanning program for the first structure according to the alignment mark of the first structure; The defects on the surface of the first structure are scanned according to the scanning program of the first structure.

2. The wafer defect detection method according to claim 1, characterized in that: The method further comprises: When it is determined that the first structure of the wafer to be inspected does not correspond to all the second structures in the structural program library, the first structure is used as a new group of second structures, the scanning program corresponding to the first structure is used as a new group of second structures The scanning program, the new group of second structures and the new group of second structures The scanning program is added to the structural program library.

3. The wafer defect detection method according to claim 1, characterized in that: Determining whether the first structure of the wafer to be inspected corresponds to a second structure in the structure library includes: Determine whether the first structure of the wafer to be inspected is the same as or similar to a second structure in the structure library.

4. The wafer defect detection method according to claim 1, characterized in that: There is an alignment mark on the surface of the second structure, and the scanning program corresponding to the second structure includes an alignment program generated according to the alignment mark of the second structure.

5. The wafer defect detection method according to claim 4, characterized in that: The alignment mark of the first structure and the alignment mark of the second structure have an outline pattern; The contour pattern of the alignment mark of the first structure is the same as the contour pattern of the alignment mark of the second structure.

6. The wafer defect detection method according to claim 5, characterized in that: The outline pattern of the alignment mark is a centrally symmetrical pattern, a number or a pattern with a special shape.

7. The wafer defect detection method according to claim 1, characterized in that: Scanning defects on the surface of the first structure according to the scanning program of the first structure includes: Generate a photographing program according to the scanning program of the first structure; Obtain defect photos of the first structure surface according to the photographing program.

8. A wafer defect detection system, characterized in that: include: A structure program library, a structure judgment module and a scanning module, wherein the structure program library includes a plurality of groups of second structures, each group of second structures includes at least one second structure, and each second structure corresponds to a scanning program; The structure judgment module is used for: Determining whether a first structure of a wafer to be inspected corresponds to a second structure in the structure library, wherein the wafer to be inspected includes a first structure, and an alignment mark is provided on a surface of the first structure; When it is determined that the first structure of the wafer to be inspected corresponds to a second structure in the structure program library, obtaining a scanning program corresponding to the second structure as a scanning program for the first structure; When it is determined that the first structure of the wafer to be inspected does not correspond to any second structure in the structure program library, generating a scanning program for the first structure according to the alignment mark of the first structure; The scanning module is used to scan defects on the surface of the first structure according to a scanning program of the first structure.

9. The wafer defect detection system according to claim 8, characterized in that: When the structure judgment module determines that the first structure of the wafer to be inspected does not correspond to all the second structures in the structure program library, the first structure is used as a new group of second structures, the scanning program corresponding to the first structure is used as a new group of second structures The scanning program, the new group of second structures and the new group of second structures The scanning program is added to the structure program library.

10. The wafer defect detection system according to claim 8, characterized in that: The surface of the second structure has an alignment mark, and the alignment mark of the first structure and the alignment mark of the second structure have a contour pattern; The contour pattern of the alignment mark of the first structure is the same as the contour pattern of the alignment mark of the second structure.

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