Overlay precision measurement mark and its use method and device

Abstract

This application belongs to the field of semiconductor device technology and specifically discloses an overlay precision measurement mark, a method for using the mark, and a device. The overlay precision measurement mark uses a DBO mark and an IBO mark in the chip edge area, which helps reduce the scribe line area used in the overlay precision measurement mark and improves the accuracy of overlay precision measurement in the scribe line area.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and specifically relates to an overlay precision measurement mark and a method and device for using the same. Background Art

[0002] With the development of semiconductor technology, the requirements for silicon wafer overlay accuracy are becoming increasingly higher. Traditional overlay accuracy measurement methods based on image processing have problems such as poor accuracy and large space occupation. Summary of the Invention

[0003] The technical purpose of the present application is to at least solve the problem of low accuracy when measuring overlay precision within the Scribe Line (located in the chip edge area).

[0004] The above objectives are achieved through the following technical solutions: In the first aspect, the present application provides an overlay precision measurement mark, comprising:

[0005] Base, first layer image mark and second layer image mark;

[0006] The first layer of image marks is located on either side of the substrate; the first layer of image marks includes a first central image and a first outer image surrounding the first central image;

[0007] The second layer of image marks is located on a surface of the first layer of image marks facing away from the substrate, the second layer of image marks including a second central image and a second outer image surrounding the second central image;

[0008] The orthographic projection of the first central image on the base overlaps with the orthographic projection of the second central image on the base;

[0009] The orthographic projection of the first outer image on the substrate does not overlap with the orthographic projection of the second outer image on the substrate;

[0010] The orthographic projection of the first outer image on the base is far away from the orthographic projection of the first central image on the base; the orthographic projection of the second outer image on the base is close to the orthographic projection of the first central image on the base;

[0011] The first central image and / or the second central image are images obtained using the principle of optical diffraction;

[0012] The first outer side image and / or the second outer side image are images obtained based on image overlay measurement.

[0013] In some embodiments, the first central image and / or the second central image includes a first grating unit and a second grating unit;

[0014] The first grating unit includes a first grating extending along the second direction and arranged at intervals in the first direction;

[0015] The second grating unit includes a second grating extending along the first direction and arranged at intervals in the second direction;

[0016] The first direction is different from the second direction.

[0017] In some embodiments, the first central image and the second central image each include N first grating elements and N second grating elements, where N is an even number.

[0018] In some embodiments, the first grating units and the second grating units are alternately arranged in the first direction and / or the second direction.

[0019] In some embodiments, the first outer image includes a third grating unit and a fourth grating unit;

[0020] The third grating unit includes a third grating extending along the second direction and arranged at intervals in the first direction;

[0021] The fourth grating unit includes a fourth grating extending along the first direction and arranged at intervals in the second direction;

[0022] and / or;

[0023] The second outer image includes a fifth grating unit and a sixth grating unit;

[0024] The fifth grating unit includes a fifth grating, the fifth grating extending along the second direction and arranged at intervals in the first direction;

[0025] The sixth grating unit includes sixth gratings extending along the first direction and arranged at intervals in the second direction.

[0026] In some embodiments, the third grating and the fourth grating surround the periphery of the first central image, and the third grating and the fourth grating are alternately distributed around the periphery of the first central image;

[0027] and / or;

[0028] The fifth grating and the sixth grating surround the periphery of the second central image, and the fifth grating and the sixth grating are alternately distributed around the periphery of the second central image.

[0029] In some embodiments, the first grating and / or the second grating has a line width W1;

[0030] The third grating and / or the fourth grating and / or the fifth grating and / or the sixth grating have a line width W2;

[0031] W1 is smaller than W2.

[0032] In some embodiments, the third grating and / or the fourth grating and / or the fifth grating and / or the sixth grating has a line width W2;

[0033] There is a spacing D between each adjacent third grating and / or between each adjacent fourth grating and / or between each adjacent fifth grating and / or between each adjacent sixth grating;

[0034] W2 / D is 0.9:1.1.

[0035] A second aspect of the present application is to provide a method for using the overlay accuracy measurement mark described in the first aspect, comprising:

[0036] providing a substrate;

[0037] Placing a first layer of image marks and a second layer of image marks of required sizes on the substrate;

[0038] After the photolithographic exposure, the overlay accuracy of the second layer image mark is confirmed using the first center image in the first layer image mark and the second center image in the second layer image mark;

[0039] After etching, overlay accuracy measurement is performed based on the first outer image in the first layer of image marks and the second outer image in the second layer of image marks.

[0040] The third aspect of the present application is to provide a semiconductor device, which is manufactured after confirmation using the overlay accuracy measurement mark described in the first aspect.

[0041] Beneficial technical effects of this application:

[0042] The overlay accuracy measurement mark provided in the present application is conducive to reducing the Scribe Line area used in the overlay accuracy measurement mark and improving the accuracy of overlay accuracy measurement in the Scribe Line area. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to denote the same components. In the drawings:

[0044] Figure 1 Schematically shows the structure of the overlay accuracy measurement mark of some embodiments of the present application;

[0045] Figure 2A Schematically shows the structure of the first part of the overlay accuracy measurement mark of some embodiments of the present application;

[0046] Figure 2B Schematically shows the structure of the second part of the overlay accuracy measurement mark of some embodiments of the present application;

[0047] Figure 3 Schematically shows the structure of the overlay accuracy measurement mark of some embodiments of the present application;

[0048] Figure 4 The following schematically shows a process flow chart of a method for using the overlay accuracy measurement mark in some embodiments of the present application.

[0049] Among them, the numbers in the accompanying drawings are as follows:

[0050] 10. Overlay precision measurement mark;

[0051] 100, base;

[0052] 200, first layer image mark; 210, first central image; 220, first outer image; 221, third grating unit; 222, fourth grating unit; 221a, third grating; 222a, fourth grating;

[0053] 300, second layer image mark; 310, second central image; 320, second outer image; 321, fifth grating element; 322, sixth grating element; 321a, fifth grating; 322a, sixth grating;

[0054] 211 or 311, a first grating unit; 212 or 312, a second grating unit;

[0055] 211a or 311a, first grating; 212a or 312a, second grating;

[0056] First direction: coordinate axis x direction;

[0057] Second direction: coordinate axis y direction. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of this application more clearly understood, this application is further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0059] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments of the present disclosure. These figures are not drawn to scale, and for the purpose of clarity, certain details are exaggerated and certain details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0060] In the context of this application, when a layer / element is referred to as being "on" another layer / element, it can be directly on the other layer / element or an intervening layer / element may be present therebetween. In addition, if a layer / element is "on" another layer / element in one orientation, it may be "below" the other layer / element when the orientation is reversed.

[0061] This application may use the term "coupled with," along with its derivatives. "Coupled" may mean one or more of the following. "Coupled" may mean that two or more elements are in direct physical or electrical contact. However, "coupled" may also mean that two or more elements are in indirect contact with each other, yet still cooperate or interact with each other, and may mean that one or more other elements are coupled or connected between the elements said to be coupled to each other. The term "directly coupled" may mean that two or more elements are in direct contact.

[0062] The development of semiconductor technology is often limited to the advancement of photolithography. The shrinking feature size places increasingly stringent demands on silicon wafer overlay accuracy. If the overlay accuracy between photolithography layers fails to meet design guidelines, it can lead to functional failures of front-end devices and back-end interconnects, directly resulting in a loss of product yield. The overlay accuracy requirements of the photolithography process are proportional to the semiconductor process node, meaning that higher technology nodes require more precise overlay accuracy.

[0063] The traditional overlay accuracy measurement method based on image processing mainly adopts a standard optical microscope system under bright field, uses a white light source and performs automatic focusing through an interferometer during the measurement process. IBO (Image-Based Overlay Mark) consists of two layers, inner and outer, representing the front layer or the current layer respectively. Its graphic feature is a grating structure with periodic lines and spaces. By acquiring the image and calculating the center position of the front layer and the current layer, the corresponding displacement deviation is obtained and decomposed into the X and Y directions. The advantage of IBO is that it can provide intuitive image information, which is easy to analyze and process. However, the disadvantage of IBO is that the measurement accuracy of small-size features is limited and the requirements for the imaging system are high.

[0064] Compared to traditional IBO measurement marks, DBO (Diffraction-Based Overlay Mark) utilizes the principles of optical diffraction to achieve higher measurement accuracy and precision, enabling more accurate characterization of the product's current layer and the overlay accuracy of previous and subsequent layers. DBO offers advantages such as high measurement accuracy and minimal environmental impact. However, its disadvantages include higher cost, sensitivity to the underlying structure, and potential inaccurate measurement results after etching.

[0065] In the manufacture of critical layers, IBO and DBO are usually used to ensure that enough marks are inserted into the Scribe Line in the exposure area for accurate overlay measurement. Scribe Line is an area on the wafer used to separate different chips. These areas are usually located at the edge of the chip and are not used to form the active area of ​​the final product, but are used as cutting channels. These areas are usually used to place various measurement and test marks: these test marks are used to monitor and control parameters in the manufacturing process, such as film thickness, etching depth, photolithography alignment, etc. Photolithography alignment marks are used to ensure precise alignment between different layers during the photolithography process.

[0066] With the popularity of high-density chips (HOC, High Overlay Critical), the requirements for overlay accuracy are further improved, resulting in the need for more overlay marks in the exposure area. This makes the space for scribe lines tight, and thus reduces accuracy.

[0067] In order to solve the above technical problems, the present application provides an overlay precision measurement mark, such as Figure 1As shown, the overlay accuracy measurement mark 10 includes a substrate 100, a first layer of image marks 200, and a second layer of image marks 300. The first layer of image marks 200 is located on either side of the substrate 100. The first layer of image marks 200 includes a first central image 210 and a first outer image 220 surrounding the first central image 210. The second layer of image marks 300 is located on the side of the first layer of image marks 200 facing away from the substrate 100. The second layer of image marks 300 includes a second central image 310 and a second outer image 320 surrounding the second central image 310. The orthographic projection of the first central image 210 on the substrate overlaps with the orthographic projection of the second central image 310 on the substrate. The overlap here includes complete overlap, and the figures also illustrate the manner of complete overlap. In addition, the orthographic projections of the images on the substrate in the figures are numbered the same as the images themselves, and no additional distinction is made in this application. The orthographic projections of the first outer image 220 on the substrate 100 do not overlap with the orthographic projections of the second outer image 320 on the substrate 100. The overlap here includes complete non-overlap. The orthographic projection of the first outer image 220 on the substrate 100 is far away from the orthographic projection of the first central image 210 on the substrate 100; the orthographic projection of the second outer image 320 on the substrate 100 is close to the orthographic projection of the first central image 310 on the substrate 100; the first central image 210 and / or the second central image 310 are images obtained using the optical diffraction principle (DBO); the first outer image 220 and / or the second outer image 320 are images obtained based on image overlay measurement (IBO).

[0068] The overlay accuracy measurement mark provided in the present application adopts a reasonable matching method of DBO and IBO, wherein the DBO and IBO marks are located in the same coordinate axis, which is conducive to establishing reasonable measurement parameters. At the same time, the area of ​​the Scribe Line used in the overlay accuracy measurement mark is reduced, and the accuracy is improved; in addition, even when the measurement of the DBO mark in the center image fails, the mark damage can be indirectly predicted through the IBO mark in the outer image. Therefore, the present application has good application prospects in the field of semiconductor devices.

[0069] In some embodiments, combined Figure 1 、 Figure 2A and Figure 2BAs can be seen, the first central image 210 and / or the second central image 310 include first grating elements 211 or 311 and second grating elements 212 or 312. This application assumes that the first central image 210 and the second central image 310 include the same grating elements, thus adopting a design approach of identical naming but different numbering. This application uses any of these numberings in the following text. Specifically, the first grating elements 211 include first gratings 211a extending along the second direction and spaced apart in the first direction. The second grating elements 212 include second gratings 212a extending along the first direction and spaced apart in the second direction. The first direction is different from the second direction. In a specific embodiment, this application assumes that the first direction and the second direction are perpendicular.

[0070] The first and second grating elements 211, 212 of the present application are located in the central region, which helps reduce the area of ​​the scribe line. Furthermore, the first and second grating elements 211, 212 each contain the same or different numbers of first gratings 211a and second gratings 212a. For any first grating element 211, the spacing between adjacent first gratings 211a is equal. Similarly, for any second grating element 212, the spacing between adjacent second gratings 212a is equal. This design approach further reduces the area of ​​the scribe line used.

[0071] In some embodiments, combined Figure 1 、 Figure 2A and Figure 2B As can be seen, the first central image 210 and the second central image 310 each include N first grating elements 211 and N second grating elements 212, where N is an even number. In this application, the number of first grating elements 211 and second grating elements 212 is affected by the actual arrangement of the grating elements. For example, in the drawings, this application illustrates N as 2.

[0072] In some embodiments, the first grating units 211 and the second grating units 212 are arranged alternately in the first direction and / or the second direction. Figure 2A FIG. 2 shows that the first grating units 211 are located at the upper left and lower right of the first central image 210 . Similarly, the second grating units 212 are located at the upper right and lower left of the first central image 210 . This design method is beneficial for reducing the area of ​​the Scribe Line used.

[0073] In some embodiments, the first outer image 220 includes a third grating unit 221 and a fourth grating unit 222. The third grating unit 221 includes third gratings 221a extending along the second direction and arranged at intervals in the first direction. The fourth grating unit 222 includes fourth gratings 222a extending along the first direction and arranged at intervals in the second direction.

[0074] This design method adopted in this application is beneficial to reducing the area of ​​​​the Scribe Line used.

[0075] In some embodiments, the second outer image 320 includes fifth grating elements 321 and sixth grating elements 322. The fifth grating elements 321 include fifth gratings 321a extending along the second direction and spaced apart in the first direction. The sixth grating elements 322 include sixth gratings 322a extending along the first direction and spaced apart in the second direction. This design approach employed by the present application also helps reduce the area of ​​the scribe line used.

[0076] In some embodiments, the third grating 221 a and the fourth grating 222 a surround the periphery of the first central image 210 , and the third grating 221 a and the fourth grating 222 a are alternately distributed around the periphery of the first central image 210 .

[0077] In some embodiments, the fifth grating 321 a and the sixth grating 322 a surround the periphery of the second central image 310 , and the fifth grating 321 a and the sixth grating 322 a are alternately distributed around the periphery of the second central image 310 .

[0078] In some embodiments, the first grating 211a and / or the second grating 212a has a line width W1;

[0079] The third grating 221a and / or the fourth grating 222a and / or the fifth grating 321a and / or the sixth grating 322a have a line width W2; W1 is smaller than W2.

[0080] In these embodiments, the present application describes the first grating 211a and the second grating 212a as having the same line width. Line width here refers to the relatively smaller distance between two opposing end faces of the grating along the first or second direction. A relatively larger distance can be referred to as line length. Specific numerical values ​​will be described in subsequent embodiments. Similarly, the third grating 221a, / or the fourth grating 222a, / or the fifth grating 321a, and / or the sixth grating 322a also have the same line width.

[0081] In this application, the grating line width of the central image is selected to be smaller than the grating line width of the outer images. This design method is beneficial for overlay precision measurement marks and also helps to improve measurement accuracy.

[0082] In some embodiments, the third grating 221a and / or the fourth grating 222a and / or the fifth grating 321a and / or the sixth grating 322a have a line width W2; there is a spacing D between each adjacent third grating 221a and / or each adjacent fourth grating 222a and / or each adjacent fifth grating 321a and / or each adjacent sixth grating 322a; and W2 / D is 0.9:1.1.

[0083] In a specific embodiment of the present application, W2 / D can be adjusted to an appropriate specific value to achieve relatively good overlay accuracy measurement while meeting product design requirements and process conditions.

[0084] The second aspect of the present application is to provide a method for using the overlay accuracy measurement mark described in the first aspect, such as Figure 4 The schematic includes the following steps:

[0085] S100, providing a substrate;

[0086] S200, placing a first layer of image marks and a second layer of image marks of required sizes on the substrate;

[0087] S300, after photolithography exposure, using a first central image in the first layer image mark and a second central image in the second layer image mark to confirm the overlay accuracy of the second layer image mark;

[0088] S400 , after etching, performing overlay accuracy measurement based on the first outer image in the first layer of image marks and the second outer image in the second layer of image marks.

[0089] Example 1

[0090] An overlay accuracy measurement mark 10 is provided, which includes a substrate 100, a first layer image mark 200, and a second layer image mark 300, wherein the first layer image mark 200 is located on either side surface of the substrate 100; the first layer image mark 200 includes a first central image 210 and a first outer image 220 surrounding the first central image 210; the second layer image mark 300 is located on the side surface of the first layer image mark 200 facing away from the substrate 100, and includes a second central image 310 and a second outer image 320 surrounding the second central image 310; the orthographic projection of the first central image 210 on the substrate overlaps with the orthographic projection of the second central image 310 on the substrate; the overlap here includes complete overlap, and the accompanying drawings also illustrate the manner of complete overlap. In addition, the orthographic projection of the image on the substrate in the accompanying drawings is consistent with the numbering used for the image itself, and no additional distinction is made in this application. The orthographic projection of the first outer image 220 on the substrate 100 does not overlap with the orthographic projection of the second outer image 320 on the substrate 100; overlap here includes no overlap at all. Furthermore, the orthographic projection of the first outer image 220 on the substrate 100 is far from the orthographic projection of the first central image 210 on the substrate 100; the orthographic projection of the second outer image 320 on the substrate 100 is close to the orthographic projection of the first central image 310 on the substrate 100; the first central image 210 and / or the second central image 310 are images obtained using the principle of optical diffraction (DBO); and the first outer image 220 and / or the second outer image 320 are images obtained based on image-based overlay measurement (IBO).

[0091] Meanwhile, first central image 210 includes two first grating elements 211 and two second grating elements 212, and second central image 310 includes two first grating elements 311 and two second grating elements 312. The two first grating elements 311 or 211 are located at the upper left and lower right of the image, respectively. Similarly, the two second grating elements 312 or 212 are located at the upper right and lower left of the image, respectively. Furthermore, first grating elements 211 include 13 first gratings 211a, and first grating elements 311 include 13 first gratings 311a. First central image 210 occupies an area of ​​16 μm × 16 μm within the region formed by the first and second directions.

[0092] Furthermore, the first outer image 220 includes two third grating elements 221 and two fourth grating elements 222. The two third grating elements 221 are located at the upper left and lower right of the image, respectively. Similarly, the two fourth grating elements 222 are located at the upper right and lower left of the image, respectively. Furthermore, the third grating elements 221 include eleven third gratings 221a, and the fourth grating elements 222 include eleven fourth gratings 222a. The second outer image 320 includes two fifth grating elements 321 and two sixth grating elements 322. The two fifth grating elements 321 are located at the upper left and lower right of the image, respectively. Similarly, the two sixth grating elements 322 are located at the upper right and lower left of the image, respectively. Furthermore, the fifth grating elements 321 include eleven fifth gratings 321a, and the sixth grating elements 322 include eleven sixth gratings 322a.

[0093] In this embodiment, the present application also provides that the third grating 221a and / or the fourth grating 222a and / or the fifth grating 321a and / or the sixth grating 322a have a line width W2 of 2 μm and a line length of 1 μm.

[0094] In this embodiment, the present application further provides that the area occupied by the substrate 100 in the region formed by the first direction and the second direction is 30 μm×30 μm, wherein the distance between the third grating unit 221 and the end edge of the substrate 100 extending in the first direction and / or the second direction is 1.25 μm. Similarly, the distance between the fourth grating unit 222 and the end edge of the substrate 100 extending in the first direction and / or the second direction is 1.25 μm.

[0095] In this embodiment, the present application also provides that the distance between the first central image 210 and / or the second central image 310 and the fifth grating element 321 and / or the sixth grating element 322 of the second layer image mark 300 is 1.25 μm.

[0096] In this embodiment, the present application also provides that the distance between the third grating unit 221 and the fifth grating unit 321 is 0.5 μm, and the distance between the fourth grating unit 222 and the sixth grating unit 322 is 0.5 μm.

[0097] And / or the distance between the fourth grating unit 222 and the fifth grating unit 321 and / or the sixth grating unit 322 is 0.5 μm.

[0098] In summary, the overlay accuracy measurement mark provided in the present application is conducive to reducing the Scribe Line area used in the overlay accuracy measurement mark and improving the accuracy of overlay accuracy measurement in the Scribe Line area.

[0099] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a," "an," and "said" as used herein may also be intended to include the plural forms. The terms "comprise," "include," "contain," and "have" are inclusive and therefore specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as requiring them to be performed in the specific order described or illustrated, unless an order of execution is explicitly indicated. It should also be understood that additional or alternative steps may be used. The above description is merely a preferred embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included within the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. An overlay precision measurement mark, characterized by: include: Base, first layer image mark and second layer image mark; The first layer of image marks is located on either side of the substrate; The first layer of image marks includes a first central image and a first outer image surrounding the periphery of the first central image; The second layer of image marks is located on a side of the first layer of image marks facing away from the substrate, and the second layer of image marks includes a second central image and a second outer image surrounding the periphery of the second central image; The orthographic projection of the first central image on the substrate overlaps with the orthographic projection of the second central image on the substrate; The orthographic projection of the first outer image on the substrate does not overlap with the orthographic projection of the second outer image on the substrate; and an orthographic projection of the first outer image on the substrate is away from an orthographic projection of the first central image on the substrate; The orthographic projection of the second outer image on the substrate is close to the orthographic projection of the first central image on the substrate; The first central image and / or the second central image are images obtained using the principle of optical diffraction; The first outer side image and / or the second outer side image are images obtained based on image overlay measurement.

2. The overlay precision measurement mark according to claim 1, characterized in that: The first central image and / or the second central image includes a first grating unit and a second grating unit; The first grating unit includes a first grating, the first grating extending along the second direction and arranged at intervals in the first direction; The second grating unit includes a second grating, the second grating extending along the first direction and arranged at intervals in the second direction; The first direction is different from the second direction.

3. The overlay precision measurement mark according to claim 2, characterized in that: The first central image and the second central image each include N first grating elements and N second grating elements; N is an even number.

4. The overlay accuracy measurement mark according to any one of claims 2 to 3, characterized in that: The first grating units and the second grating units are alternately arranged in a first direction and / or a second direction.

5. The overlay accuracy measurement mark according to any one of claims 2 to 3, characterized in that: The first outer image includes a third grating unit and a fourth grating unit; The third grating unit includes a third grating, and the third grating extends along the second direction and is arranged at intervals in the first direction; The fourth grating unit includes a fourth grating, and the fourth grating extends along the first direction and is arranged at intervals in the second direction; and / or; The second outer image includes a fifth grating unit and a sixth grating unit; The fifth grating unit includes a fifth grating, and the fifth grating extends along the second direction and is arranged at intervals in the first direction; The sixth grating unit includes sixth gratings, and the sixth gratings extend along the first direction and are arranged at intervals in the second direction.

6. The overlay precision measurement mark according to claim 5, characterized in that: The third grating and the fourth grating surround the periphery of the first central image, and the third grating and the fourth grating are alternately distributed around the periphery of the first central image; and / or; The fifth grating and the sixth grating surround the periphery of the second central image, and the fifth grating and the sixth grating are alternately distributed around the periphery of the second central image.

7. The overlay accuracy measurement mark according to any one of claims 5 to 6, characterized in that: The first grating and / or the second grating has a line width W1; The third grating and / or the fourth grating and / or the fifth grating and / or the sixth grating have a line width W2; W1 is smaller than W2.

8. The overlay accuracy measurement mark according to any one of claims 5 to 6, characterized in that: The third grating and / or the fourth grating and / or the fifth grating and / or the sixth grating have a line width W2; There is a spacing D between each adjacent third grating and / or between each adjacent fourth grating and / or between each adjacent fifth grating and / or between each adjacent sixth grating; W2 / D is 0.9:1.

1.

9. A method for using the overlay precision measurement mark according to claim 1, characterized in that: include: providing a substrate; placing a first layer of image marks and a second layer of image marks of required sizes on the substrate; After the photolithographic exposure, the overlay accuracy of the second layer image mark is confirmed using the first center image in the first layer image mark and the second center image in the second layer image mark; After etching, overlay accuracy measurement is performed based on the first outer image in the first layer of image marks and the second outer image in the second layer of image marks.

10. A semiconductor device, characterized in that: The method is prepared by confirming the overlay accuracy measurement mark according to any one of claims 1 to 8.

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