CN119725327B - Alignment mark layout and operation method thereof - Google Patents
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Abstract
本申请公开了一种对准标记版图及其操作方法，对准标记版图包括：第一标记，包括参考层第一标记和当前层第一标记，两者的形状和尺寸相同；多个呈旋转对称的第二标记，每个第二标记包括中间第二标记以及间隔设置的外围第二标记和内围第二标记，每个中间第二标记的位置和一个外围第二标记和内围第二标记之间的间隔的位置对应，当中间第二标记为当前层第二标记时，外围第二标记和内围第二标记构成参考层第二标记。本申请通过设置当前层和参考层上的第一标记来进行粗对准，以及设置多个呈旋转对称的第二标记，进行两次对准，以完成精确对准，从而不仅能够实现便捷粗对准，还能实现精确对准，并降低精确对准的难度，进而发挥光刻机更高的套刻潜力。
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
The application relates to the technical field of semiconductors, in particular to an alignment mark layout and an operation method thereof.
Background
In the semiconductor manufacturing process, photolithography is one of the key technologies, and in the semiconductor photolithography process, overLay accuracy (OVL) is one of the key parameters for measuring the photolithography process, which means the alignment accuracy of the back layer pattern relative to the front layer pattern in the multi-layer photolithography process, if the deviation is too large, the product yield is directly affected, and the alignment step before exposure is a key link for guaranteeing the OverLay accuracy.
Currently, the alignment before exposure is realized by utilizing the identification alignment mark (ALIGNMENT MARK, AIM), however, the alignment mark in the related art is inconvenient to operate and the alignment time is long when being used for alignment.
Disclosure of Invention
In the summary, a series of concepts in a simplified form are introduced, which will be further described in detail in the detailed description. The summary of the application is not intended to define the key features and essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
In order to solve the existing problems, an aspect of an embodiment of the present application provides an alignment mark layout, where the alignment mark layout includes:
The first mark comprises a reference layer first mark and a current layer first mark, and the shape and the size of the reference layer first mark are the same as those of the current layer first mark;
A plurality of second marks which are rotationally symmetrical,
Each second mark comprises an intermediate second mark, and a peripheral second mark and an inner peripheral second mark which are arranged at intervals, wherein the position of each intermediate second mark corresponds to the position of the interval between one peripheral second mark and one inner peripheral second mark;
Wherein when the intermediate second mark is a current layer second mark, the outer peripheral second mark and the inner peripheral second mark constitute a reference layer second mark;
when the intermediate second mark is a reference layer second mark, the outer peripheral second mark and the inner peripheral second mark constitute a current layer second mark.
In some embodiments, the current layer first mark is located at a center of rotation of the current layer second mark, and the reference layer first mark is located at a center of rotation of the reference layer second mark.
In some embodiments, the extending directions of two adjacent inner peripheral second marks in the second marks are perpendicular to each other, the extending directions of two adjacent outer peripheral second marks in the second marks are perpendicular to each other, and the extending direction of the inner peripheral second marks in each second mark is parallel to the extending direction of the outer peripheral second marks.
In some embodiments, the intermediate second marks comprise a plurality of intermediate bar marks distributed in parallel at equal intervals, each of the inner second marks comprises a plurality of inner bar marks distributed in parallel at equal intervals, and each of the outer second marks comprises a plurality of outer bar marks distributed in parallel at equal intervals.
In some embodiments, the middle bar mark, the inner bar mark and the outer bar mark are the same in size, and 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 equal.
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.
In some embodiments, the number of the second marks in the alignment mark layout is four.
In some embodiments, the first marker is a cross, the cross being a center symmetrical pattern.
In some examples, the cross-shaped sub-marks include two intersecting bar-shaped sub-marks, each having a length ranging from 2um to 3um and a width ranging from 0.4um to 0.6um.
On the other hand, the embodiment of the application provides an operation method based on the alignment mark layout, wherein the alignment mark layout is used for an alignment process;
the operation method comprises the following steps:
forming a reference layer and a current layer on a wafer respectively, wherein 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 when the reference layer is formed, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern comprises a peripheral second mark pattern and an inner peripheral second mark pattern, and 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 when the current layer is formed, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern comprises the peripheral second mark pattern and the inner peripheral second mark pattern;
If the first mark pattern of the reference layer is overlapped with the first mark pattern of the current layer, determining that the alignment precision of the current layer and the reference layer meets the preset condition, or,
If the reference layer first mark pattern and the current layer first mark pattern are overlapped, determining a first distance difference value between the central point of the peripheral second mark pattern and the central point of the middle second mark pattern;
If the first distance difference value meets a preset first threshold value requirement, determining a second distance difference value between the center point of the inner periphery second mark pattern and the center point of the middle second mark pattern;
and if the second distance difference value meets a preset second threshold requirement, determining that the alignment precision of the overlay between the current layer and the reference layer meets a preset precision requirement.
The application provides an alignment mark layout, which is characterized in that rough alignment of a current layer and a reference layer is performed by arranging first marks on the current layer and the reference layer, and a plurality of rotationally symmetrical second marks are arranged, wherein each second mark comprises a middle second mark, and a periphery second mark and an inner periphery second mark which are arranged at intervals, and the periphery second mark and the inner periphery second mark are respectively used for performing alignment with the middle second mark for two times so as to finish accurate alignment, thereby not only realizing convenient rough alignment, but also realizing accurate alignment, reducing the difficulty of accurate alignment, and further exerting higher alignment potential of a photoetching machine.
Drawings
The following drawings are included to provide an understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the application and their description to explain the principles of the application. In the accompanying drawings:
FIG. 1 shows an alignment mark layout in the related art;
FIG. 2 is a schematic diagram of an alignment mark layout according to an embodiment of the present application;
FIG. 3 is a schematic diagram of an alignment mark structure of a current layer in an alignment mark layout according to an embodiment of the present application;
FIG. 4 is a schematic diagram of an alignment mark structure of a reference layer in an alignment mark layout according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a structure of a peripheral second mark and an intermediate second mark of an alignment mark layout according to an embodiment of the present application when performing alignment;
FIG. 6 is a schematic diagram of the structure of an inner second mark and an intermediate second mark of an alignment mark layout according to an embodiment of the present application when performing alignment;
FIG. 7 is a flowchart of a first method of operation based on an alignment mark layout in accordance with one embodiment of the present application;
FIG. 8 is a flow chart illustrating a second method of operation of an alignment mark-based layout in accordance with one embodiment of the present application.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the application may be practiced without one or more of these details. In other instances, well-known features have not been described in detail in order to avoid obscuring the application.
It should be understood that the present application may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art. In the drawings, the size of layers and regions, as well as the relative sizes, may be exaggerated for clarity. Like numbers refer to like elements throughout.
It will be understood that when an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.
Spatially relative terms, such as "under," "below," "beneath," "under," "above," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below" and "under" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In semiconductor manufacturing, photolithography is one of the key technologies, and on one hand, the rapid development of photolithography technology provides technical support for producing integrated circuits with higher integration, and on the other hand, the strong desire of the current market for new technology nodes promotes the rapid development of photolithography technology. In the important workflow of photolithography, photoresist is coated on a wafer, and then steps such as exposure, development, baking and the like are performed on the wafer, so that a design pattern on a photomask (mask) can be transferred onto the photoresist, therefore, photolithography is an important link in a semiconductor manufacturing process, in the semiconductor photolithography process, alignment is an extremely important step, and an alignment process is tightly combined with operations such as etching coating and the like performed in a processing area, so that the accuracy of chip processing is determined. OverLay accuracy (OVL) is one of key parameters for measuring a photolithography process, and is the alignment accuracy of a rear layer pattern relative to a front layer pattern in a multi-layer photolithography process, if the deviation is too large, the product yield is directly affected, and an alignment step before exposure is a key link for guaranteeing the OverLay accuracy.
Currently, the alignment before exposure is realized by identifying an alignment mark (ALIGNMENT MARK, AIM), as shown in fig. 1, which is an alignment mark layout of the related art, an alignment result is obtained by an error between a center point of a current layer mark 20 and a center point of a reference layer mark 10, and when the error meets a preset threshold requirement, it is indicated that the alignment precision meets the requirement. However, when alignment marks in the related art are used for alignment, for products with low alignment accuracy requirements, the alignment process cannot be quickly and conveniently completed through coarse alignment, and for products with high alignment accuracy requirements, quick and accurate alignment is difficult to achieve.
Therefore, in view of the foregoing technical problems, an embodiment of the present application proposes an alignment mark layout, which includes:
The first mark comprises a reference layer first mark and a current layer first mark, and the shape and the size of the reference layer first mark are the same as those of the current layer first mark;
a plurality of rotationally symmetrical second marks, wherein each second mark comprises a middle second mark, and a peripheral second mark and an inner peripheral second mark which are arranged at intervals, and the position of each middle second mark corresponds to the position of the interval between one peripheral second mark and one inner peripheral second mark;
Wherein when the intermediate second mark is a current layer second mark, the outer peripheral second mark and the inner peripheral second mark constitute a reference layer second mark;
when the intermediate second mark is a reference layer second mark, the outer peripheral second mark and the inner peripheral second mark constitute a current layer second mark.
According to the alignment mark layout provided by the application, the rough alignment of the current layer and the reference layer is performed by setting the first marks on the current layer and the reference layer, and a plurality of rotationally symmetrical second marks are set, each second mark comprises a middle second mark, and a periphery second mark and an inner periphery second mark which are arranged at intervals, and the periphery second mark and the inner periphery second mark are respectively used for performing alignment with the middle second mark for two times so as to finish accurate alignment, thereby not only realizing convenient rough alignment, but also realizing accurate alignment, reducing the difficulty of accurate alignment, and further exerting higher alignment potential of a photoetching machine.
It should be noted that the current layer and the reference layer of the present application may be interchanged, and the middle second mark is used as the second mark of the current layer, and the outer second mark and the inner second mark form the second mark of the reference layer to describe the illustration of the specific embodiment.
Next, the alignment mark layout according to the embodiment of the present application will be described in detail with reference to fig. 2 to 6.
As shown in fig. 2, fig. 2 is a schematic structural diagram of an alignment mark layout according to an embodiment of the present application, where the alignment mark layout includes a first mark 100 and a plurality of rotationally symmetrical second marks 200, and the first mark 100 includes a reference layer first mark and a current layer first mark, and in this embodiment, the first mark 100 shown in fig. 2 is a schematic diagram after the reference layer first mark 110 shown in fig. 3 overlaps with the current layer first mark 120 shown in fig. 4. The reference layer first mark 110 and the current layer first mark 120 are identical in shape and size.
Each second mark comprises an intermediate second mark 220, and a peripheral second mark 211 and an inner second mark 212 which are arranged at intervals, wherein the position of each intermediate second mark 220 corresponds to the position of the interval between one peripheral second mark 211 and one inner second mark 212, when the intermediate second mark 220 is a current layer second mark, the peripheral second mark 211 and the inner second mark 212 form a reference layer second mark, and when the intermediate second mark 220 is a reference layer second mark, the peripheral second mark 211 and the inner second mark 212 form a current layer second mark, namely the reference layer second mark and the current layer second mark can be interchanged.
It should be noted that the inner second mark means a second mark near the rotation center, and the outer second mark means a second mark far from the rotation center. It should be noted that, the reference layer may be the nearest film layer formed by using an etching process before the current layer is formed, that is, the film layer immediately before the current layer is formed, and the current layer is formed in the next step after the reference layer is formed, so that when the current layer is formed, the operations of alignment, measurement and the like can still be performed by using the first mark pattern of the reference layer and the second mark pattern of the reference layer formed by the first mark of the reference layer and the second mark pattern of the reference layer.
When the alignment mark layout is used for alignment, the first mark is used for rough alignment, for products with low alignment precision requirements, whether the alignment precision meets the requirements can be judged according to the alignment result of the first mark, and for products with high alignment precision requirements, the second mark is used for fine alignment twice to obtain more accurate alignment precision, so that the alignment mark layout provided by the embodiment of the application can realize quick and convenient rough alignment and fine alignment to obtain more accurate alignment precision.
Illustratively, as shown in FIG. 3, the reference layer first mark 110 is located at the center of rotation of the reference layer second mark, and as shown in FIG. 4, the current layer first mark 120 is located at the center of rotation of the current layer second mark. Through setting up the rotation center at the second mark with first mark, can make second mark evenly distributed and avoid appearing partial second mark far away from first mark, the condition that partial second mark is too near to first mark to help can more effective alignment when using this alignment mark, improve alignment and measuring accuracy. 2-4, the first indicia 100 is of a cross-type or other suitable shape, the cross-type comprising two intersecting bar-shaped sub-indicia intersecting at a center to form a center-symmetrical cross-type pattern. In one example, each bar sub-mark has a length ranging from 2um to 3um, for example, the bar sub-mark has a length ranging from 2um, 2.5um, or 3um, and each bar sub-mark has a width ranging from 0.4um to 0.6um, for example, the bar sub-mark has a width ranging from 0.4um, 0.5um, or 0.6um. The alignment marks are usually arranged on the dicing streets, so that the problems of overlarge occupied total space and low space utilization rate easily occur, and meanwhile, the alignment marks also need to be clearly identified by a scanning device, so that the sizes of the strip-shaped sub-marks and the strip-shaped marks to be described later and the sizes of the adjacent strip-shaped sub-marks or the intervals between the adjacent strip-shaped marks need to be limited.
Illustratively, as shown in fig. 2, the number of second marks 200 in the alignment mark layout is four or other suitable number, as shown in fig. 3, the extending directions a of two adjacent inner peripheral second marks 212 in the second marks 200 are perpendicular to each other, the extending directions B of two adjacent outer peripheral second marks 211 in the second marks 200 are perpendicular to each other, in other words, the rotation angle of the rotational symmetry of the second marks 200 is 90 degrees, and as further shown in fig. 3, the extending direction a of the inner peripheral second marks 212 in each second mark 200 is parallel to the extending direction B of the outer peripheral second marks 211. The alignment mark layout is obtained by adopting the rotation symmetrical arrangement of the 90-degree rotation angle, and compared with other proper angles, the alignment mark layout comprises four second marks, the extending directions of the adjacent second marks are mutually perpendicular to form marks, the process is more beneficial to realizing, and meanwhile, the extending directions of the inner peripheral second marks and the extending directions of the outer peripheral second marks in the same second mark are parallel, so that the two fine alignments of the middle second marks can be quickly completed during alignment, and further, the more accurate alignment precision can be quickly obtained.
Illustratively, as shown in fig. 2-6, the intermediate second marks 220 comprise a plurality of intermediate bar marks 2201 distributed in parallel at equal intervals, each of the inner second marks 212 comprises a plurality of inner bar marks 2102 distributed in parallel at equal intervals, and each of the outer second marks 211 comprises a plurality of outer bar marks 2101 distributed in parallel at equal intervals. In one embodiment of the present application, the number of the middle bar marks of each middle second mark, the number of the inner bar marks of each inner second mark, and the number of the outer bar marks of each outer second mark are all 5, or other suitable numbers may be adopted according to actual needs. It should be noted that, the extending direction refers to the direction in which the bar marks (the middle bar mark or the inner bar mark or the outer bar mark, and the following are arranged at intervals in sequence). The middle bar marks, the inner peripheral bar marks and the outer peripheral bar marks are the same in size, and the interval between two adjacent middle bar marks, the interval between two adjacent inner peripheral bar marks and the interval between two adjacent outer peripheral bar marks are equal. In one example, the length of the bar mark ranges from 3um to 4um, such as 3um, 3.5um, or 4um in length, the width of the bar mark ranges from 0.8um to 1.2um, such as 0.8um, 1um, or 1.2um in width, and the spacing of two adjacent bar marks ranges from 0.8um to 1.2um, such as 0.8um, 1um, or 1.2um in spacing of two adjacent bar marks.
Thus, the description of the structure of the alignment mark layout according to an embodiment of the present application is completed, and the complete alignment mark layout may further include other constituent structures, which are not described in detail herein.
The embodiment of the application also provides an operation method based on the alignment mark layout, wherein the alignment mark layout is used for an alignment process, and for a product with low alignment precision requirement, as shown in fig. 7, the operation method comprises the following steps:
step S710, respectively forming a reference layer and a current layer on a wafer, wherein 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 when the reference layer is formed, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern comprises a peripheral second mark pattern and an inner peripheral second mark pattern, and 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 when the current layer is formed, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern comprises the peripheral second mark pattern and the inner peripheral second mark pattern;
Step 720, if the first mark pattern of the reference layer is overlapped with the first mark pattern of the current layer, determining that the alignment accuracy of the current layer and the reference layer meets a preset condition.
In this embodiment, only the first mark pattern of the reference layer and the first mark pattern of the current layer are needed to be roughly aligned, specifically, alignment data of the first mark pattern of the current layer and the first mark pattern of the reference layer are collected by using an alignment observation device, if the first mark pattern of the reference layer and the first mark pattern of the current layer coincide, it is indicated that the current layer and the reference layer are aligned, alignment accuracy of alignment of the current layer and the reference layer meets a preset condition, and a subsequent photolithography process can be performed. If the deviation of the first mark pattern of the reference layer and the first mark pattern of the current layer exceeds a preset range, the misalignment of the current layer and the reference layer is indicated, and the current layer and the reference layer are required to be realigned until the alignment precision of the alignment of the current layer and the reference layer meets a preset condition. It should be noted that the overlapping means that the substantial overlap or the overlapping degree is within a prescribed range.
For more products, the requirement on alignment accuracy is higher, and photolithography is performed only by one coarse alignment, which may bring about larger deviation of processing accuracy, so that finer alignment is required, and thus in some embodiments, as shown in fig. 8, the operation method based on the alignment mark layout includes:
Step 810, respectively forming a reference layer and a current layer on a wafer, wherein 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 when the reference layer is formed, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern comprises a peripheral second mark pattern and an inner peripheral second mark pattern, and 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 when the current layer is formed, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern comprises the peripheral second mark pattern and the inner peripheral second mark pattern;
step S820, if the reference layer first mark pattern and the current layer first mark pattern are overlapped, determining a first distance difference value between the central point of the peripheral second mark pattern and the central point of the middle second mark pattern;
Step S830, if the first distance difference meets a preset first threshold requirement, determining a second distance difference between the center point of the inner second mark pattern and the center point of the middle second mark pattern;
Step S840, if the second distance difference meets a preset second threshold requirement, determining that the alignment precision of the overlay between the current layer and the reference layer meets a preset precision requirement.
It is worth mentioning that the reference layer second mark and the current layer second mark may be interchanged, i.e. when the middle second mark is the reference layer second mark, the outer periphery second mark and the inner periphery second mark constitute the current layer second mark, in which case 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 when the reference layer is formed, i.e. when the current layer is formed, 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, the current layer second mark pattern comprises the outer periphery second mark pattern and the inner periphery second mark pattern, and when the reference layer second mark is constituted by the outer periphery second mark and the inner periphery second mark, the middle second mark is the current layer second mark, in which case 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 pattern, i.e. when the reference layer first mark and the reference layer second mark pattern are formed, the middle second mark pattern is formed based on the first periphery second mark pattern and the current layer second mark pattern.
In this embodiment, first coarse alignment is performed through the first mark pattern, if coarse alignment is qualified, first fine alignment is performed according to the peripheral second mark pattern and the middle second mark pattern, if first fine alignment is qualified, second fine alignment is performed according to the inner peripheral second mark pattern and the middle second mark pattern, after the second fine alignment is qualified, it is finally determined that alignment accuracy between the current layer and the reference layer meets a preset accuracy requirement, and in this process, if alignment failure occurs, the coarse alignment and the fine alignment need to be performed again after the re-alignment is performed.
Specifically, the coarse alignment judges whether the coarse alignment is qualified by referring to whether the first mark pattern of the layer is overlapped with the first mark pattern of the current layer, the first fine alignment is performed on the basis of the qualification of the coarse alignment, the first fine alignment is as shown in fig. 5, the data (for example, coordinate values) of the center point of the second mark pattern on the periphery and the center point of the second mark pattern in the middle are obtained through an alignment process observation device, then the distance difference between the center point of the second mark pattern on the periphery and the center point of the second mark pattern in the middle is calculated and recorded as a first distance difference, the first distance difference is compared with a first threshold, and if the first distance difference is within the first threshold range, the second mark pattern on the periphery and the second mark pattern in the middle can be considered to be aligned.
And then, performing second fine alignment, wherein the second fine alignment is as shown in fig. 6, acquiring data (for example, coordinate values) of the center point of the inner second mark pattern and the center point of the middle second mark pattern through an alignment process observation device, calculating a distance difference value between the center point of the inner second mark pattern and the center point of the middle second mark pattern, recording the distance difference value as a second distance difference value, comparing the second distance difference value with a second threshold value, if the second distance difference value is within the second threshold value range, considering that the inner second mark pattern is aligned with the middle second mark pattern, and finishing the second fine alignment until the alignment is finished, thereby determining that the alignment precision between the current layer and the reference layer meets the preset precision requirement, if the second distance difference value exceeds the second threshold value range, indicating that the alignment precision between the current layer and the reference layer does not meet the preset precision requirement, and if the alignment is disqualified. It should be noted that the preset accuracy requirement may be determined according to a priori experience, which is not specifically limited herein.
Thus, the description of the operation method based on the alignment mark layout according to the embodiment of the present application is completed, and the complete operation method may further include other steps, which are not described in detail herein, but it should be noted that the sequence of the steps may be adjusted on the premise of no conflict.
According to the alignment mark layout and the operation method thereof, the first marks on the current layer and the reference layer are arranged to perform coarse alignment on the current layer and the reference layer, and a plurality of rotationally symmetrical second marks are arranged, each second mark comprises a middle second mark, a periphery second mark and an inner periphery second mark which are arranged at intervals, and the periphery second mark and the inner periphery second mark are respectively used for performing twice alignment with the middle second mark so as to finish accurate alignment, so that the coarse alignment is convenient and rapid, the accurate alignment is also realized, the difficulty of accurate alignment is reduced, and the higher overlay potential of the photoetching machine is further exerted.
It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.
The above description is merely illustrative of the embodiments of the present application and the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes or substitutions are covered by the protection scope of the present application. The protection scope of the application is subject to the protection scope of the claims.
Claims (8)
1. An alignment mark layout, comprising:
The first mark comprises a reference layer first mark and a current layer first mark, and the shape and the size of the reference layer first mark are the same as those of the current layer first mark;
A plurality of rotationally symmetrical second marks, each second mark comprising an intermediate second mark, and a peripheral second mark and an inner second mark which are arranged at intervals, wherein the position of each intermediate second mark corresponds to the position of the interval between one peripheral second mark and one inner second mark, and the second marks are used for performing fine alignment twice;
Wherein when the intermediate second mark is a current layer second mark, the outer peripheral second mark and the inner peripheral second mark constitute a reference layer second mark;
when the middle second mark is a reference layer second mark, the outer periphery second mark and the inner periphery second mark form a current layer second mark;
The alignment mark layout comprises four second marks, and the rotation angles of the four second marks, which are rotationally symmetrical, are 90 degrees;
The reference layer first mark is positioned at the rotation center of the reference layer second mark, and the current layer first mark is positioned at the rotation center of the current layer second mark so as to uniformly distribute the second marks;
The second mark is used for fine alignment twice and comprises the steps of 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, acquiring data of central points of peripheral second mark patterns and central points of middle second mark patterns, calculating a first distance difference value between the central points of the peripheral second mark patterns and the central points of middle second mark patterns, comparing the first distance difference value with a first threshold range, considering that the peripheral second mark patterns are aligned with the middle second mark patterns if the first distance difference value is within the first threshold range, acquiring data of central points of inner peripheral second mark patterns and data of central points of middle second mark patterns, calculating a second distance difference value between the central points of the inner peripheral second mark patterns and the central points of middle second mark patterns, comparing the second distance difference value with a second threshold range, and considering that the inner peripheral second mark patterns are aligned with the middle second mark patterns if the second distance difference value is within the second threshold range.
2. The alignment mark layout according to claim 1, wherein the extending directions of two adjacent inner peripheral second marks in the second marks are perpendicular to each other, the extending directions of two adjacent outer peripheral second marks in the second marks are perpendicular to each other, and the extending directions of the inner peripheral second marks in each of the second marks are parallel to the extending directions of the outer peripheral second marks.
3. The alignment mark layout according to claim 1, wherein the intermediate second marks comprise a plurality of intermediate bar marks distributed in parallel at equal intervals, each of the inner second marks comprises a plurality of inner bar marks distributed in parallel at equal intervals, and each of the outer second marks comprises a plurality of outer bar marks distributed in parallel at equal intervals.
4. The alignment mark layout according to claim 3, wherein the intermediate bar marks, the inner bar marks and the outer bar marks have the same size, and the interval between two adjacent intermediate bar marks, the interval between two adjacent inner bar marks and the interval between two adjacent outer bar marks are equal.
5. The alignment mark layout according to claim 4, wherein the length of the intermediate bar mark ranges from 3um to 4um, the width of the intermediate bar mark ranges from 0.8um to 1.2um, and the interval between two adjacent intermediate bar marks ranges from 0.8um to 1.2um.
6. The alignment mark layout according to claim 1, wherein the first mark is a cross, and the cross is a centrosymmetric pattern.
7. The alignment mark layout according to claim 6, wherein the cross comprises two crossed bar-shaped 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 of operation based on an alignment mark layout according to any one of claims 1 to 7, wherein the alignment mark layout is used for an overlay alignment process;
the operation method comprises the following steps:
Forming a reference layer and a current layer on a wafer respectively, wherein 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 when the reference layer is formed, wherein the reference layer second mark pattern is an intermediate second mark pattern or the reference layer second mark pattern comprises a peripheral second mark pattern and an inner peripheral second mark pattern, and 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 when the current layer is formed, wherein the current layer second mark pattern is the intermediate second mark pattern or the current layer second mark pattern comprises the peripheral second mark pattern and the inner peripheral second mark pattern;
If the first mark pattern of the reference layer is overlapped with the first mark pattern of the current layer, determining that the alignment precision of the current layer and the reference layer meets the preset condition, or,
If the reference layer first mark pattern and the current layer first mark pattern are overlapped, determining a first distance difference value between the central point of the peripheral second mark pattern and the central point of the middle second mark pattern;
If the first distance difference value meets a preset first threshold value requirement, determining a second distance difference value between the center point of the inner periphery second mark pattern and the center point of the middle second mark pattern;
and if the second distance difference value meets a preset second threshold requirement, determining that the alignment precision of the overlay between the current layer and the reference layer meets a preset precision requirement.
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| CN118377187A (en) * | 2024-04-30 | 2024-07-23 | 物元半导体技术(青岛)有限公司 | Overlay mark structure and overlay compensation method |
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| DE102005046973B4 (en) * | 2005-09-30 | 2014-01-30 | Globalfoundries Inc. | A structure and method for simultaneously determining overlay accuracy and pattern placement error |
| CN1963679A (en) * | 2006-11-24 | 2007-05-16 | 上海微电子装备有限公司 | Alignment mark structure for aligning wafer |
| KR102094974B1 (en) * | 2013-03-08 | 2020-03-30 | 삼성전자주식회사 | Methods for overlay measurements |
| CN105573049A (en) * | 2014-11-07 | 2016-05-11 | 西南科技大学 | Proximity nano-lithography double grating automatic alignment marks |
| US10811362B2 (en) * | 2019-01-09 | 2020-10-20 | United Microelectronics Corp. | Overlay mark structure and measurement method thereof |
| US11726410B2 (en) * | 2021-04-20 | 2023-08-15 | Kla Corporation | Multi-resolution overlay metrology targets |
| CN116344511B (en) * | 2022-12-28 | 2024-04-19 | 荣芯半导体(淮安)有限公司 | Alignment mark layout and operation method thereof |
| CN116960112A (en) * | 2023-07-27 | 2023-10-27 | 上海集成电路装备材料产业创新中心有限公司 | Overlay mark based on diffraction |
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| CN118377187A (en) * | 2024-04-30 | 2024-07-23 | 物元半导体技术(青岛)有限公司 | Overlay mark structure and overlay compensation method |
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