A kind of alignment mark layout and operation method thereof

Abstract

The present application discloses an alignment mark layout and an operation method thereof, wherein the alignment mark layout comprises: a first mark, including a reference layer first mark and a current layer first mark, both of which have the same shape and size; a plurality of rotationally symmetrical second marks, each of which comprises an intermediate second mark and an outer second mark and an inner second mark that are spaced apart, the position of each intermediate second mark corresponds to the position of the space between an outer second mark and an inner second mark, and when the intermediate second mark is the current layer second mark, the outer second mark and the inner second mark constitute the reference layer second mark. The present application performs coarse alignment by setting the first mark on the current layer and the reference layer, and performs two alignments by setting a plurality of rotationally symmetrical second marks to complete precise alignment, thereby achieving not only convenient coarse alignment, but also precise alignment, and reducing the difficulty of precise alignment, thereby giving full play to the higher overlay potential of the lithography machine.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to an alignment mark layout and an operation method thereof. Background Art

[0002] In the semiconductor manufacturing process, photolithography is one of the key technologies. In the semiconductor photolithography process, overlay accuracy (OVL) is one of the key parameters to measure the photolithography process. It refers to the alignment accuracy of the rear layer pattern relative to the front layer pattern in the multi-layer photolithography process. If the deviation is too large, it will directly affect the product yield. The alignment step before exposure is the key link to ensure overlay accuracy.

[0003] Currently, the art uses an alignment mark (AIM) to achieve alignment before exposure. However, the operation of overlay alignment using the alignment mark in the related art is inconvenient and the overlay alignment time is long. Summary of the invention

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] In view of the existing problems, an embodiment of the present application provides an alignment mark layout on one hand, and the alignment mark layout includes:

[0006] A first mark, including a reference layer first mark and a current layer first mark, wherein the reference layer first mark and the current layer first mark have the same shape and size;

[0007] A plurality of rotationally symmetric second marks,

[0008] Each of the second marks includes a middle second mark and a peripheral second mark and an inner second mark arranged at intervals, and the position of each of the middle second marks corresponds to the position of the interval between one of the peripheral second marks and the inner second mark;

[0009] Wherein, when the middle second mark is the second mark of the current layer, the outer second mark and the inner second mark constitute the second mark of the reference layer;

[0010] When the middle second mark is the reference layer second mark, the outer second mark and the inner second mark constitute the current layer second mark.

[0011] In some embodiments, the current layer first mark is located at the rotation center of the current layer second mark, and the reference layer first mark is located at the rotation center of the reference layer second mark.

[0012] In some embodiments, the extension directions of two adjacent inner second marks in the second marks are perpendicular to each other, the extension directions of two adjacent outer second marks in the second marks are perpendicular to each other, and the extension direction of the inner second mark in each second mark is parallel to the extension direction of the outer second mark.

[0013] In some embodiments, the middle second mark includes multiple middle bar marks distributed in parallel at equal intervals; each of the inner second marks includes multiple inner bar marks distributed in parallel at equal intervals; and each of the outer second marks includes multiple outer bar marks distributed in parallel at equal intervals.

[0014] In some embodiments, the middle bar mark, the inner bar mark and the outer bar mark have the same size; the interval between two adjacent middle bar marks, the interval between two adjacent inner bar marks and the interval between two adjacent outer bar marks are all equal.

[0015] In some embodiments, the length of the middle bar mark ranges from 3um to 4um, the width of the middle bar mark ranges from 0.8um to 1.2um, and the interval between two adjacent middle bar marks ranges from 0.8um to 1.2um.

[0016] In some embodiments, the number of the second marks in the alignment mark layout is four.

[0017] In some embodiments, the first mark is a cross shape, and the cross shape is a centrally symmetrical figure.

[0018] In some examples, the cross-shaped mark includes two crossed bar sub-marks, each of which has a length ranging from 2um to 3um, and each of which has a width ranging from 0.4um to 0.6um.

[0019] Another aspect of the embodiment of the present application provides an operation method based on the above alignment mark layout, wherein the alignment mark layout is used for an overlay alignment process;

[0020] The operation method comprises:

[0021] A reference layer and a current layer are formed on a wafer respectively, wherein when forming the reference layer, a reference layer first mark pattern and a reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern includes an outer second mark pattern and an inner second mark pattern, and when forming the current layer, a current layer first mark pattern and a current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern includes the outer second mark pattern and the inner second mark pattern;

[0022] If the first marking pattern of the reference layer and the first marking pattern of the current layer coincide with each other, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets a preset condition; or,

[0023] If the reference layer first marking pattern and the current layer first marking pattern coincide with each other, determining a first distance difference between a center point of the peripheral second marking pattern and a center point of the middle second marking pattern;

[0024] If the first distance difference meets the preset first threshold requirement, determining a second distance difference between the center point of the inner second marking pattern and the center point of the middle second marking pattern;

[0025] If the second distance difference meets a preset second threshold requirement, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets a preset accuracy requirement.

[0026] The present application provides an alignment mark layout, which performs coarse alignment of the current layer and the reference layer by setting a first mark on the current layer and the reference layer, and sets a plurality of rotationally symmetrical second marks, each of which includes a middle second mark and an outer second mark and an inner second mark that are spaced apart. The outer second mark and the inner second mark are respectively used to perform two alignments with the middle second mark to complete precise alignment, thereby achieving not only convenient coarse alignment but also precise alignment, and reducing the difficulty of precise alignment, thereby giving full play to the higher overlay potential of the lithography machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following drawings of the present application are used as part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, and are used to explain the principles of the present application. In the drawings:

[0028] Figure 1 An alignment mark layout in the related art is shown;

[0029] Figure 2A schematic diagram showing the structure of an alignment mark layout according to a specific embodiment of the present application is shown;

[0030] Figure 3 A schematic diagram of the alignment mark structure of the current layer in the alignment mark layout of a specific embodiment of the present application is shown;

[0031] Figure 4 A schematic diagram of the alignment mark structure of the reference layer in the alignment mark layout of a specific embodiment of the present application is shown;

[0032] Figure 5 A schematic diagram showing the structure of the outer second mark and the middle second mark of the alignment mark layout of a specific embodiment of the present application when performing overlay alignment;

[0033] Figure 6 A schematic diagram showing the structure of an inner second mark and a middle second mark of an alignment mark layout according to a specific embodiment of the present application when performing overlay alignment;

[0034] Figure 7 A flowchart of a first operation method based on an alignment mark layout in a specific embodiment of the present application is shown;

[0035] Figure 8 A flow chart of a second operation method based on an alignment mark layout in a specific embodiment of the present application is shown. DETAILED DESCRIPTION

[0036] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0037] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0038] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part.

[0039] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0040] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0041] In the semiconductor manufacturing process, photolithography is one of the key technologies. On the one hand, the rapid development of photolithography technology provides technical support for the production of integrated circuits with higher integration. On the other hand, the strong market expectations for new technology nodes have promoted the rapid development of photolithography technology. In this important work process of photolithography, it is necessary to first coat the wafer with photoresist, and then perform exposure, development, baking and other steps to transfer the design pattern on the mask to the photoresist. It can be seen that photolithography is an important link in the semiconductor process. In the semiconductor photolithography process, alignment is an extremely important step. The alignment process is closely combined with subsequent operations such as etching and coating in the processing area, which will determine the accuracy of chip processing. Overlay (OVL) is one of the key parameters for measuring the photolithography process. It is the alignment accuracy of the rear layer pattern relative to the front layer pattern in the multi-layer photolithography process. If the deviation is too large, it will directly affect the product yield. The alignment step before exposure is the key link to ensure the overlay accuracy.

[0042] At present, the art uses the recognition of alignment marks (Alignment Mark, AIM) to achieve alignment before exposure, such as Figure 1 The figure shows an alignment mark layout of a related art, and the alignment result is obtained by the error between the center point of the current layer mark 20 and the center point of the reference layer mark 10. When the error meets the preset threshold requirement, it means that the alignment accuracy meets the requirement. However, when the alignment mark in the related art is used for overlay alignment, for products with low alignment accuracy requirements, it is impossible to quickly and conveniently complete the alignment process through coarse alignment, and for products with high alignment accuracy requirements, it is also difficult to achieve fast and accurate alignment.

[0043] Therefore, in view of the existence of the aforementioned technical problems, an embodiment of the present application proposes an alignment mark layout, which includes:

[0044] A first mark, including a reference layer first mark and a current layer first mark, wherein the reference layer first mark and the current layer first mark have the same shape and size;

[0045] A plurality of rotationally symmetrical second marks, each of the second marks comprising a middle second mark and a peripheral second mark and an inner second mark arranged at intervals, wherein the position of each of the middle second marks corresponds to the position of the interval between one of the peripheral second marks and the inner second mark;

[0046] Wherein, when the middle second mark is the second mark of the current layer, the outer second mark and the inner second mark constitute the second mark of the reference layer;

[0047] When the middle second mark is the reference layer second mark, the outer second mark and the inner second mark constitute the current layer second mark.

[0048] According to the alignment mark layout provided in the present application, coarse alignment of the current layer and the reference layer is performed by setting first marks on the current layer and the reference layer, and a plurality of rotationally symmetrical second marks are set, each of the second marks includes a middle second mark and a peripheral second mark and an inner second mark that are spaced apart, and the peripheral second mark and the inner second mark are respectively used to perform two alignments with the middle second mark to complete precise alignment, thereby achieving not only convenient coarse alignment but also precise alignment, and reducing the difficulty of precise alignment, thereby giving play to the higher overlay potential of the lithography machine.

[0049] It is worth mentioning that the current layer and the reference layer of the present application can be interchanged. In the diagram of the present application, the middle second mark is used as the current layer second mark, and the outer second mark and the inner second mark constitute the reference layer second mark as a diagram of a specific embodiment for description.

[0050] Below, reference Figures 2 to 6 The alignment mark layout of the embodiment of the present application is described in detail.

[0051] like Figure 2 As shown, Figure 2 is a schematic diagram of the structure of an alignment mark layout in an embodiment of the present application, the alignment mark layout includes: a first mark 100 and a plurality of rotationally symmetrical second marks 200, wherein the first mark 100 includes a reference layer first mark and a current layer first mark. In this embodiment, Figure 2 The first mark 100 shown is Figure 3 The reference layer first mark 110 is shown with Figure 4 The schematic diagram of the first mark 120 of the current layer after being overlapped is shown. The first mark 110 of the reference layer and the first mark 120 of the current layer have the same shape and size.

[0052] Each of the second marks includes an intermediate second mark 220 and an outer second mark 211 and an inner second mark 212 that are spaced apart, and the position of each intermediate second mark 220 corresponds to the position of the interval between the outer second mark 211 and the inner second mark 212; wherein, when the intermediate second mark 220 is the second mark of the current layer, the outer second mark 211 and the inner second mark 212 constitute the second mark of the reference layer; when the intermediate second mark 220 is the second mark of the reference layer, the outer second mark 211 and the inner second mark 212 constitute the second mark of the current layer, that is, the reference layer second mark and the current layer second mark are interchangeable.

[0053] It is worth mentioning that the inner second mark refers to the second mark close to the rotation center, and the outer second mark refers to the second mark far from the rotation center. It is worth mentioning that the reference layer can be the nearest film layer formed by etching process before forming the current layer, that is, the previous film layer next to the current layer. After the reference layer is formed, the current layer is formed in the next step, so when forming the current layer, the reference layer first mark pattern and the reference layer second mark pattern formed by the reference layer first mark and the reference layer second mark can still be used for alignment, measurement and other operations.

[0054] When using the alignment mark layout for alignment, the first mark is used for coarse alignment. For products that do not require high overlay alignment accuracy, it can be judged whether the overlay alignment accuracy meets the requirements based on the alignment result of the first mark. For products that require high overlay alignment accuracy, it is necessary to perform two fine alignments using the second mark to obtain more accurate overlay alignment accuracy. Therefore, the alignment mark layout provided in the embodiment of the present application can not only achieve fast and convenient coarse alignment but also achieve fine alignment to obtain more accurate overlay alignment accuracy.

[0055] For example, Figure 3 As shown, the reference layer first mark 110 is located at the rotation center of the reference layer second mark, as shown in FIG. Figure 4 As shown, the first mark 120 of the current layer is located at the rotation center of the second mark of the current layer. By setting the first mark at the rotation center of the second mark, the second marks can be evenly distributed to avoid the situation where some second marks are too far from the first mark and some second marks are too close to the first mark, thereby facilitating more effective alignment when using the alignment mark and improving the accuracy of alignment and measurement. For example, Figure 2-Figure 4 As shown, the first mark 100 is a cross shape or can also be other suitable shapes. The cross shape includes two crossed bar sub-marks, and the two bar sub-marks intersect at the center to form a centrally symmetrical cross-shaped figure. In one example, the length range of each bar sub-mark is 2um-3um, for example, the length of the bar sub-mark is 2um, 2.5um or 3um, and the width range of each bar sub-mark is 0.4um-0.6um, for example, the width of the bar sub-mark is 0.4um, 0.5um or 0.6um. Usually, the alignment mark is set on the cutting path, which is prone to occupying too much total space and low space utilization. At the same time, the alignment mark also needs to be clearly identified by the scanning device. Therefore, it is necessary to limit the size of the bar sub-mark and the bar mark described later, as well as the spacing between adjacent bar sub-marks or adjacent bar marks.

[0056] For example, Figure 2 As shown, the number of the second marks 200 in the alignment mark layout is four or may be other suitable numbers, such as Figure 3As shown, the extension directions A of two adjacent inner second marks 212 in the second mark 200 are perpendicular to each other, and the extension directions B of two adjacent outer second marks 211 in the second mark 200 are perpendicular to each other. In other words, the rotation angle of the rotational symmetry of the second mark 200 is 90 degrees, and continues as Figure 3 As shown, in each second mark 200, the extension direction A of the inner second mark 212 is parallel to the extension direction B of the outer second mark 211. The alignment mark layout includes four second marks by adopting a rotation angle of 90 degrees for rotational symmetry. Compared with adopting other appropriate angles, the extension directions of adjacent second marks are perpendicular to each other to form marks, which is more conducive to process implementation. At the same time, in the same second mark, the extension direction of the inner second mark is parallel to the extension direction of the outer second mark, which is conducive to quickly completing the two fine alignments of the middle second mark during alignment, thereby quickly obtaining more accurate overlay alignment accuracy.

[0057] For example, Figure 2-Figure 6 As shown, the middle second mark 220 includes a plurality of middle bar marks 2201 distributed in parallel at equal intervals; each of the inner second marks 212 includes a plurality of inner bar marks 2102 distributed in parallel at equal intervals; each of the outer second marks 211 includes a plurality of outer bar marks 2101 distributed in parallel at equal intervals. In one embodiment of the present application, the number of middle bar marks of each middle second mark, the number of inner bar marks of each inner second mark, and the number of outer bar marks of each outer second mark are all 5, or other suitable numbers can be used according to actual needs. It is worth mentioning that the extension direction mentioned above refers to the direction in which the bar marks (middle bar marks or inner bar marks or outer bar marks, the same below) are arranged in sequence. Exemplarily, the sizes of the middle bar marks, the inner bar marks, and the outer bar marks are the same; the intervals between two adjacent middle bar marks, the intervals between two adjacent inner bar marks, and the intervals between two adjacent outer bar marks are all equal. In one example, the length range of the bar mark is 3um-4um, for example, its length is 3um, 3.5um or 4um, the width range of the bar mark is 0.8um-1.2um, for example, its width is 0.8um, 1um or 1.2um, and the interval between two adjacent bar marks is 0.8um-1.2um, for example, the interval between two adjacent bar marks is 0.8um, 1um or 1.2um.

[0058] So far, the description of the structure of the alignment mark layout according to an embodiment of the present application has been completed. A complete alignment mark layout may also include other component structures, which will not be described one by one here.

[0059] The embodiment of the present application also provides an operation method based on the above alignment mark layout, which is used in the overlay alignment process. For products with low overlay alignment accuracy requirements, such as Figure 7 As shown, the operation method includes:

[0060] Step S710: forming a reference layer and a current layer on the wafer respectively, wherein when forming the reference layer, a reference layer first mark pattern and a reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern includes an outer second mark pattern and an inner second mark pattern, and when forming the current layer, a current layer first mark pattern and a current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern includes the outer second mark pattern and the inner second mark pattern;

[0061] Step S720: If the first marking pattern of the reference layer and the first marking pattern of the current layer coincide with each other, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets a preset condition.

[0062] In this embodiment, it is only necessary to perform a rough alignment between the first mark pattern of the reference layer and the first mark pattern of the current layer. Specifically, an overlay alignment observation device is used to collect the alignment data of the first mark pattern of the current layer and the first mark pattern of the reference layer. If the first mark pattern of the reference layer and the first mark pattern of the current layer coincide with each other, it means that the current layer and the reference layer have been aligned, and the overlay alignment accuracy between the current layer and the reference layer meets the preset conditions, and subsequent photolithography processes can be performed. If the deviation between the first mark pattern of the reference layer and the first mark pattern of the current layer exceeds the preset range, it means that the current layer and the reference layer are not aligned, and the current layer and the reference layer need to be realigned until the overlay alignment accuracy between the current layer and the reference layer meets the preset conditions. It is worth mentioning that overlap refers to substantial overlap or the degree of overlap is within a specified range.

[0063] For more products, the requirements for overlay alignment accuracy before photolithography are higher. Photolithography with only one rough alignment may lead to a large processing accuracy deviation. Therefore, a more precise overlay alignment is required. Therefore, in some embodiments, such as Figure 8 As shown, the operation method based on the above alignment mark layout includes:

[0064] Step S810: forming a reference layer and a current layer on the wafer respectively, wherein when forming the reference layer, a reference layer first mark pattern and a reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern includes an outer second mark pattern and an inner second mark pattern, and when forming the current layer, a current layer first mark pattern and a current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern includes the outer second mark pattern and the inner second mark pattern;

[0065] Step S820: If the reference layer first marking pattern and the current layer first marking pattern coincide with each other, determining a first distance difference between a center point of the outer second marking pattern and a center point of the middle second marking pattern;

[0066] Step S830: if the first distance difference meets the preset first threshold requirement, determining a second distance difference between the center point of the inner second marking pattern and the center point of the middle second marking pattern;

[0067] Step S840: If the second distance difference meets the preset second threshold requirement, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets the preset accuracy requirement.

[0068] It is worth mentioning that the second mark of the reference layer and the second mark of the current layer can be interchanged, that is, when the middle second mark is the second mark of the reference layer, the outer second mark and the inner second mark constitute the second mark of the current layer. In this case, when forming the reference layer, the reference layer first mark pattern and the reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, and the reference layer second mark pattern is the middle second mark pattern. When forming the current layer, the current layer first mark pattern and the current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, and the current layer second mark pattern includes the outer second mark pattern. and the inner second mark pattern; and when the reference layer second mark is composed of the outer second mark and the inner second mark, the middle second mark is the current layer second mark. In this case, when forming the reference layer, the reference layer first mark pattern and the reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, and the reference layer second mark pattern includes the outer second mark pattern and the inner second mark pattern. When forming the current layer, the current layer first mark pattern and the current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, and the current layer second mark pattern is the middle second mark pattern.

[0069] In this embodiment, a coarse alignment is first performed using the first mark pattern. If the coarse alignment is qualified, a first fine alignment is performed based on the outer second mark pattern and the middle second mark pattern. If the first fine alignment is qualified, a second fine alignment is performed based on the inner second mark pattern and the middle second mark pattern. After the second fine alignment is qualified, it is finally determined that the overlay alignment accuracy between the current layer and the reference layer meets the preset accuracy requirement. During this process, as long as the alignment fails, realignment is required before coarse alignment and fine alignment are performed again.

[0070] Specifically, the rough alignment determines whether the rough alignment is qualified by whether the first mark pattern of the reference layer and the first mark pattern of the current layer overlap, and the first fine alignment is performed on the basis of the qualified rough alignment. Figure 5 As shown, through the overlay alignment process observation equipment, the data (such as coordinate values) of the center point of the peripheral second mark pattern and the center point of the middle second mark pattern are obtained, and then the distance difference between the center point of the peripheral second mark pattern and the center point of the middle second mark pattern is calculated, recorded as the first distance difference, and the first distance difference is compared with the first threshold value. If the first distance difference is within the first threshold range, it can be considered that the peripheral second mark pattern is aligned with the middle second mark pattern.

[0071] Next, a second fine alignment is performed. Figure 6 As shown, through the overlay alignment process observation equipment, the data (such as coordinate values) of the center point of the inner second mark pattern and the center point of the middle second mark pattern are obtained, and then the distance difference between the center point of the inner second mark pattern and the center point of the middle second mark pattern is calculated, recorded as the second distance difference, and the second distance difference is compared with the second threshold value. If the second distance difference is within the second threshold range, it can be considered that the inner second mark pattern and the middle second mark pattern are aligned, and the second fine alignment is qualified. At this point, the alignment is completed, thereby determining that the overlay alignment accuracy between the current layer and the reference layer meets the preset accuracy requirements. If the second distance difference exceeds the second threshold range, it means that the overlay alignment accuracy between the current layer and the reference layer does not meet the preset accuracy requirements, and the alignment is unqualified. It is worth mentioning that the preset accuracy requirements can be determined based on prior experience, and are not specifically limited here.

[0072] So far, the description of the operating method based on the aforementioned alignment mark layout according to an embodiment of the present application has been completed. The complete operating method may also include other steps, which will not be described one by one here. It is worth mentioning that the order of the above steps can be adjusted without conflict.

[0073] The alignment mark layout and operation method thereof provided in the embodiment of the present application perform coarse alignment of the current layer and the reference layer by setting a first mark on the current layer and the reference layer, and set a plurality of rotationally symmetric second marks, each of which includes a middle second mark and an outer second mark and an inner second mark that are spaced apart, and the outer second mark and the inner second mark are respectively used to perform two alignments with the middle second mark to complete precise alignment, thereby achieving not only convenient coarse alignment but also precise alignment, and reducing the difficulty of precise alignment, thereby giving play to the higher overlay potential of the lithography machine.

[0074] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation on the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present application may be implemented with the aid of hardware including several different elements and with the aid of appropriately programmed computers. In a unit claim listing several on-board systems, several of these on-board systems may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0075] The above is only a specific implementation method or description of a specific implementation method of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An alignment mark layout, characterized in that: include: A first mark, including a reference layer first mark and a current layer first mark, wherein the reference layer first mark and the current layer first mark have the same shape and size; A plurality of rotationally symmetrical second marks, each of the second marks comprising a middle second mark and a peripheral second mark and an inner second mark arranged at intervals, the position of each of the middle second marks corresponding to the position of the interval between one of the peripheral second mark and the inner second mark, and the second marks are used for performing two fine alignments; Wherein, when the middle second mark is the second mark of the current layer, the outer second mark and the inner second mark constitute the second mark of the reference layer; When the middle second mark is a reference layer second mark, the outer second mark and the inner second mark constitute a current layer second mark; The alignment mark pattern comprises four second marks, and the rotation angle of the four second marks is 90 degrees; The first mark of the reference layer is located at the rotation center of the second mark of the reference layer, and the first mark of the current layer is located at the rotation center of the second mark of the current layer, so that the second marks are evenly distributed; The second mark is used to perform two fine alignments, including: forming a reference layer second mark pattern and a current layer second mark pattern based on the reference layer second mark and the current layer second mark; obtaining data on the center point of the peripheral second mark pattern and the center point of the middle second mark pattern and calculating a first distance difference between the center point of the peripheral second mark pattern and the center point of the middle second mark pattern, comparing the first distance difference with a first threshold range, and if the first distance difference is within the first threshold range, it is considered that the peripheral second mark pattern is aligned with the middle second mark pattern; obtaining data on the center point of the inner second mark pattern and the center point of the middle second mark pattern and calculating a second distance difference between the center point of the inner second mark pattern and the center point of the middle second mark pattern, and comparing the second distance difference with a second threshold range, and if the second distance difference is within the second threshold range, it is considered that the inner second mark pattern is aligned with the middle second mark pattern.

2. The alignment mark layout according to claim 1, characterized in that: The extension directions of two adjacent inner second marks in the second marks are perpendicular to each other, the extension directions of two adjacent outer second marks in the second marks are perpendicular to each other, and the extension direction of the inner second mark in each second mark is parallel to the extension direction of the outer second mark.

3. The alignment mark layout according to claim 1, characterized in that: The middle second mark includes a plurality of middle bar marks which are equally spaced and parallel distributed; each of the inner second marks includes a plurality of inner bar marks which are equally spaced and parallel distributed; each of the outer second marks includes a plurality of outer bar marks which are equally spaced and parallel distributed.

4. The alignment mark layout according to claim 3, characterized in that: The sizes of the middle bar mark, the inner bar mark and the outer bar mark are the same; the interval between two adjacent middle bar marks, the interval between two adjacent inner bar marks and the interval between two adjacent outer bar marks are all equal.

5. The alignment mark layout according to claim 4, characterized in that: The length of the middle bar mark ranges from 3um to 4um, the width of the middle bar mark ranges from 0.8um to 1.2um, and the interval between two adjacent middle bar marks ranges from 0.8um to 1.2um.

6. The alignment mark layout according to claim 1, wherein: The first mark is in the shape of a cross, and the cross is a centrally symmetrical figure.

7. The alignment mark layout according to claim 6, characterized in that: The cross-shaped mark includes two crossed bar sub-marks, each of which has a length ranging from 2um to 3um and a width ranging from 0.4um to 0.6um.

8. A method for operating an alignment mark layout according to any one of claims 1 to 7, characterized in that: The alignment mark pattern is used for overlay alignment process; The operation method comprises: A reference layer and a current layer are formed on a wafer respectively, wherein when forming the reference layer, a reference layer first mark pattern and a reference layer second mark pattern are formed based on the reference layer first mark and the reference layer second mark, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern includes an outer second mark pattern and an inner second mark pattern, and when forming the current layer, a current layer first mark pattern and a current layer second mark pattern are formed based on the current layer first mark and the current layer second mark, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern includes the outer second mark pattern and the inner second mark pattern; If the first marking pattern of the reference layer and the first marking pattern of the current layer coincide with each other, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets a preset condition; or, If the reference layer first marking pattern and the current layer first marking pattern coincide with each other, determining a first distance difference between a center point of the peripheral second marking pattern and a center point of the middle second marking pattern; If the first distance difference meets the preset first threshold requirement, determining a second distance difference between the center point of the inner second marking pattern and the center point of the middle second marking pattern; If the second distance difference meets a preset second threshold requirement, it is determined that the overlay alignment accuracy between the current layer and the reference layer meets a preset accuracy requirement.

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