Preparation method of alignment mark and semiconductor structure
By obtaining the light-transmitting information of the target film layer and the alignment mark, the alignment mark is prepared in the semiconductor integrated circuit process, which solves the problem of insufficient cutting path area, and realizes effective placement of the alignment mark and signal interference avoidance.
Patent Information
- Application Number
- CN202311154194.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-07
- Publication Date
- 2025-03-07
AI Technical Summary
With the development of semiconductor integrated circuit technology, the effective area of the cutting channel is reduced, resulting in the inability to place sufficient alignment marks in the cutting channel, affecting the lithography process.
By obtaining the light-transmitting information of the target film layer and the target alignment mark, when the target alignment mark is not transparent, the target alignment mark is prepared at the preset longitudinal position to ensure that the alignment mark has the same longitudinal position as other alignment marks, saving the area occupied by the cutting channel.
The effective placement of alignment marks in the cutting path is achieved, the efficiency of the lithography process is improved, and interference of alignment mark signals is avoided.
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Figure CN119581458A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of integrated circuit technology, and in particular to a method for preparing an alignment mark and a semiconductor structure. Background Art
[0002] In the semiconductor processing process, multiple photolithography processes are usually involved. At the same time, in the photolithography process, in order to achieve the alignment of each film layer, alignment marks are usually set on each film layer. The alignment marks are usually set in the cutting path. And the alignment marks in different film layers are usually prepared at different longitudinal positions to prevent signal interference between the alignment marks of each layer.
[0003] However, with the development of semiconductor integrated circuit technology, the effective area of the available cutting path is getting smaller and smaller, resulting in insufficient area for placing alignment marks on the cutting path, thereby affecting the photolithography process. Summary of the invention
[0004] Based on this, it is necessary to provide an alignment mark structure and a preparation method thereof to address the problem that the cutting path in the prior art does not have enough area to place the alignment mark.
[0005] In order to achieve the above object, on the one hand, the present invention provides a method for preparing an alignment mark, comprising:
[0006] Acquire a target film layer, where the target film layer is a film layer on which an alignment mark is currently to be manufactured;
[0007] When the target film layer is the first film layer that needs to be provided with an alignment mark, preparing a target alignment mark of the target film layer at a preset longitudinal position;
[0008] When the target film layer is not the first film layer, obtaining light transmittance information of a target alignment mark of the target film layer;
[0009] When the alignment mark is opaque, a target alignment mark of the target film layer is prepared at the preset longitudinal position.
[0010] In one embodiment, when the target film layer is not the first film layer, before obtaining the light transmittance information of the target film layer, the method includes:
[0011] Acquire alignment mark setting information of a front film layer, where the front film layer is a film layer obtained in a preceding process of the target film layer;
[0012] When the front layer alignment mark is disposed at a preset longitudinal position on the front film layer, light transmission information of the target alignment mark of the target film layer is obtained.
[0013] In one embodiment, when the front layer alignment mark is not provided at the preset longitudinal position of the front layer film, a target alignment mark of the target film layer is prepared at the preset longitudinal position.
[0014] In one embodiment, when the target alignment mark is opaque, preparing the target alignment mark of the target film layer at a preset longitudinal position includes:
[0015] Acquiring the diffraction light intensity of the front layer alignment mark;
[0016] When the diffraction light intensity of the front layer alignment mark is higher than a preset threshold, a target alignment mark is designed to cover the front layer alignment mark in the front film layer;
[0017] A target alignment mark is prepared on the target film layer at a preset longitudinal position.
[0018] In one embodiment, when the diffraction light intensity of the front layer alignment mark is lower than a preset threshold, a target alignment mark is formed on the target film layer at the preset longitudinal position.
[0019] In one embodiment, when the target alignment mark is light-transmissive, the target alignment mark of the target film layer is formed at a longitudinal position that is offset from a preset longitudinal position.
[0020] The present invention also provides a semiconductor structure, comprising a substrate and a plurality of film layers stacked on the substrate and provided with alignment marks, wherein, among the adjacent film layers with alignment marks, one close to the substrate serves as a first film layer, and the other serves as a second film layer; the first film layer is provided with a first alignment mark at a preset longitudinal position; the second film layer is provided with a second alignment mark at the preset longitudinal position, and the second alignment mark is opaque.
[0021] In one embodiment, the second alignment mark covers the first alignment mark.
[0022] In one embodiment, the first alignment mark is opaque.
[0023] In one embodiment, the first alignment mark includes a plurality of first sub-patterns, the second alignment mark includes a plurality of second sub-patterns, the first sub-patterns are arranged opposite to the second sub-patterns, and the width of the second sub-patterns is greater than that of the first sub-patterns.
[0024] In the method for preparing the alignment mark and the semiconductor structure of the present invention, by obtaining the light transmission information of the target film layer and the target alignment mark, when a film layer is arranged below the target film layer and the film layer has the alignment mark, and the target alignment mark is not light-transmissive, the target film layer can be designed to prepare the target alignment mark at a preset longitudinal position. At this time, the target alignment mark can have the same longitudinal position as other alignment marks, thereby saving the occupied area of the alignment mark on the cutting path, and other alignment marks will not interfere with the signal of the target alignment mark. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0026] Figure 1 is a flow chart of a method for preparing an alignment mark provided in an embodiment;
[0027] Figure 2 is a flow chart of a method for preparing an alignment mark provided in another embodiment;
[0028] Figure 3 is a flow chart of a method for preparing an alignment mark provided in yet another embodiment;
[0029] Figure 4 is a schematic diagram of a semiconductor structure provided in an embodiment;
[0030] Figures 5 to 10 A schematic diagram of a structure obtained during an intermediate process of preparing a semiconductor structure provided in an embodiment.
[0031] Explanation of the accompanying drawings: semiconductor structure-100; substrate-110; first material film layer-12; first film layer-120; first alignment mark-121; first sub-pattern-1211; second material film layer-13; second film layer-130; second alignment mark-131; second sub-pattern-1311; first anti-reflection layer-140; first patterned anti-reflection layer-141; first patterned photoresist layer-150; first dielectric layer-160; second dielectric material layer-17; second dielectric layer-170; second anti-reflection layer-180; second patterned anti-reflection layer-181; second patterned photoresist layer-190; groove-200. DETAILED DESCRIPTION
[0032] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0034] It should be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or layer, or there can be intervening elements or layers. Conversely, when an element is referred to as being "directly on" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various layers, these layers should not be limited by these terms. These terms are merely used to distinguish one layer from another. Thus, the first layer discussed below may be referred to as the second layer without departing from the teachings of the present invention.
[0035] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein 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, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.
[0036] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that when the terms "consisting of" and / or "comprising" are used in this specification, the presence of the features, integers, steps, operations, elements and / or parts can be determined, but the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups is not excluded. At the same time, when used herein, the term "and / or" includes any and all combinations of the relevant listed items.
[0037] Embodiments of the invention are described herein with reference to cross-sectional views which are schematic representations of idealized embodiments (and intermediate structures) of the invention, and variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are contemplated. Thus, embodiments of the invention should not be limited to the particular shapes of the regions shown herein, but rather include deviations in shapes due to, for example, manufacturing techniques. The regions shown in the figures are schematic in nature, and their shapes do not represent the actual shapes of the regions of the device, and do not limit the scope of the invention.
[0038] As shown in the background art, with the development of semiconductor integrated circuit technology, the effective area of the available cutting path is getting smaller and smaller, resulting in insufficient area of the cutting path for placing alignment marks, thereby affecting the photolithography process.
[0039] For example, as integrated circuit devices become smaller and smaller, the area of the cutting path will decrease accordingly. At the same time, the integrated circuit includes many stacked film layers formed by photolithography. Each film layer can be set with an alignment mark in the cutting path. However, the alignment marks of different film layers cannot occupy the same longitudinal position, otherwise it will affect the recognition of the alignment marks. At this time, as the number of film layers in the integrated circuit increases, there may be insufficient area in the cutting path to place the alignment mark.
[0040] Based on this, an embodiment of the present application provides a method for preparing an alignment mark and a semiconductor structure.
[0041] In one embodiment, see Figure 1 , a method for preparing an alignment mark is provided, comprising the following steps:
[0042] Step S100: obtaining a target film layer, where the target film layer is a film layer currently to be manufactured.
[0043] Step S30: when the target film layer is the first film layer that needs to be provided with an alignment mark, preparing a target alignment mark of the target film layer at a preset longitudinal position.
[0044] Step S300: when the target film layer is not the first film layer, obtaining light transmittance information of the target alignment mark of the target film layer.
[0045] Step S400: when the target alignment mark is opaque, preparing a target alignment mark of the target film layer at a preset longitudinal position.
[0046] In step S100 , the film layer currently to be manufactured is a film layer currently required to be manufactured by a photolithography process.
[0047] For film layers that need to be manufactured through photolithography, alignment marks are usually set on the film layers. In the photolithography process, a wafer coated with photoresist and a mask are usually placed in a photolithography machine. The photolithography machine is equipped with an alignment system that can detect the alignment marks formed in the previous photolithography process.
[0048] When the alignment system detects the alignment mark, it will emit detection light to the alignment mark. The detection light is irradiated on the alignment mark and diffracted, and the alignment mark is recognized by collecting and solving the diffracted light information.
[0049] Afterwards, the photoresist is exposed and developed based on the mask, so that the pattern on the mask is transferred to the photoresist to form a patterned photoresist. Afterwards, the film material on the wafer is etched based on the patterned photoresist to form a current film layer aligned with the previous film layer.
[0050] When obtaining the target film layer, relevant information of the target film layer can be obtained. For example, whether the target film layer is the first film layer can be obtained.
[0051] In step S30, when the target film layer is the first film layer, there is no need to consider the conditions of other film layers, and the target alignment mark can be directly prepared at the preset longitudinal position. In some cases, the target film layer is the first film layer prepared on the substrate, and the target film layer is the first film layer on which the alignment mark needs to be set. As an example, the substrate can be a silicon substrate, and the target film layer is the first film layer set on the surface of the silicon substrate. At this time, the target alignment mark can be directly prepared at the preset longitudinal position. In other cases, multiple film layers have been set on the substrate, but the multiple film layers are not set with alignment marks. At this time, the target film layer is also the first film layer on which the alignment mark needs to be set.
[0052] In step S300 , when the target film layer is not the first film layer, it is necessary to obtain light transmittance information of the target alignment mark of the target film layer.
[0053] The light transmittance information of the target alignment mark may be determined based on the relevant optical properties of the target alignment mark.
[0054] As an example, the light transmittance information of the target alignment mark can be determined based on the diffraction light intensity of the target alignment mark. When the diffraction light intensity is higher than a preset threshold, the target alignment mark can be considered to be opaque. Conversely, when the diffraction light intensity is lower than the preset threshold, the target alignment mark can be considered to be translucent. The preset threshold can be set according to actual requirements. For example, the preset threshold can be 0.1% of the diffraction light intensity of the reference mark.
[0055] In step S400, when the target alignment mark is opaque, the target alignment mark of the target film layer can be directly prepared at a preset longitudinal position. The specific value of the preset longitudinal position can be set according to actual requirements.
[0056] Specifically, the semiconductor structure may have multiple film layers, and the first direction may be the stacking direction of the multiple film layers. The direction perpendicular to the first direction may be the second direction. The preset longitudinal position is the position where the coordinate of the second direction is a preset value.
[0057] At this time, it can be understood that the first direction coordinates of different film layers stacked are different. Therefore, the alignment marks of different film layers prepared at the same preset longitudinal position have the same second direction coordinates, but different first direction coordinates. At this time, the alignment marks of different film layers prepared at the same preset longitudinal position are longitudinally aligned.
[0058] Meanwhile, as an example, preparing an alignment mark of a certain film layer at a preset longitudinal position may be to set the center position of the alignment mark at the preset longitudinal position, or to set the edge position of the alignment mark at the preset longitudinal position.
[0059] Furthermore, as an example, the alignment mark may include a plurality of periodically repeated and spaced sub-patterns. In this case, preparing an alignment mark of a certain film layer at a preset longitudinal position refers to preparing a plurality of sub-patterns at the preset longitudinal position to form an overall pattern (alignment mark) together, rather than preparing each sub-pattern in the alignment mark.
[0060] In this embodiment, by judging the light transmittance information of the target alignment mark, when the target alignment mark is opaque, the target alignment mark is prepared at a preset longitudinal position of the target film layer. At this time, on the one hand, since the target alignment mark is opaque, when the alignment system detects its alignment mark, the opaque target alignment mark will not or is not easily interfered by the signal of the alignment marks of other film layers. On the other hand, when the target film layer is not the first film layer mentioned above, the target alignment mark can have the same preset longitudinal position as other alignment marks without the need for misalignment preparation, so that there can be enough area in the cutting path to place the alignment mark, so as to improve the cutting path area utilization rate.
[0061] In addition, as the area of the scribe line occupied by the alignment mark decreases, it is more conducive to setting a smaller scribe line. At this time, the wafer area occupied by the scribe line can also be reduced accordingly, and the product area can occupy a larger wafer area, thereby improving the wafer area utilization rate.
[0062] It can be understood that the above steps can be repeated to prepare the target alignment mark of each target film layer.
[0063] In one embodiment, see Figure 2 , step S400 further includes:
[0064] Step S41: when the target alignment mark is light-transmissive, preparing a target alignment mark of the target film layer at a longitudinal position that is offset from a preset longitudinal position.
[0065] When the target alignment mark is light-transmissive, the detection light of the alignment system illuminates the target alignment mark, and the light passes through the target alignment mark to illuminate the front film layer.
[0066] At this time, the target alignment mark is prepared at a longitudinal position that is offset from the preset longitudinal position, so that in the next photolithography process, when the alignment system detects the target alignment mark, the target alignment mark will not be affected by the opaque alignment mark of the previous film layer prepared at the preset longitudinal position.
[0067] In one embodiment, see Figure 3 When the target film layer is not the first film layer, before step S300, the following steps are included:
[0068] Step S200: Acquire alignment mark setting information of a previous film layer, where the previous film layer is a film layer obtained in a previous process of a target film layer.
[0069] Meanwhile, step S300 is: when the front layer alignment mark is provided at the preset longitudinal position of the front layer film layer, light transmission information of the target alignment mark of the target film layer is obtained.
[0070] When the target film layer is not the first film layer, the previous film layer is a film layer obtained in the previous process of the target film layer, that is, a film layer that has been prepared by the previous photolithography process. In addition, an alignment mark is set in the previous film layer. At this time, if the target alignment mark of the target film layer is also prepared at a preset longitudinal position, the previous alignment mark may affect the alignment system's recognition of the target alignment mark of the target film layer, thereby affecting the next photolithography process.
[0071] Therefore, at this time, step S300 needs to be performed, that is, the light transmission information of the target alignment mark needs to be obtained, and the target alignment mark is set according to the light transmission information of the target alignment mark.
[0072] When the target alignment mark is opaque, the target alignment mark and the front layer alignment mark can be prepared at a preset longitudinal position. At this time, the light diffraction signal returned by the target alignment mark collected by the alignment system will not or will not be easily interfered by the front layer alignment mark. Therefore, at this time, the target alignment mark of the target film layer can be prepared at the preset longitudinal position.
[0073] Meanwhile, as an example, after step S200, the following may also be included:
[0074] Step S31: when the current film layer has no previous alignment mark at the preset longitudinal position, preparing a target alignment mark of the target film layer at the preset longitudinal position.
[0075] When the front layer alignment mark is not set at the preset longitudinal position of the front layer film, the target alignment mark of the target film is prepared at the preset longitudinal position, and the recognition of the target alignment mark of the target film by the alignment system will not or will not be easily affected by the front layer alignment mark. Therefore, at this time, the target alignment mark of the target film can be directly prepared at the preset longitudinal position.
[0076] In one embodiment, see Figure 3 , step S400 includes:
[0077] Step S410: when the target alignment mark is opaque, obtaining the diffraction light intensity of the front layer alignment mark;
[0078] Step S420: When the diffraction light intensity of the front-layer alignment mark is higher than a preset threshold, a target alignment mark is designed to cover the front-layer alignment mark in the front film layer.
[0079] Step S430: preparing a target alignment mark of the target film layer at a preset longitudinal position.
[0080] In step S410, the light transmittance information of the front-layer alignment mark may be determined according to relevant optical properties such as the diffraction light intensity of the front-layer alignment mark.
[0081] In step S420, when the diffraction light intensity of the front layer alignment mark is higher than the preset threshold, the front layer alignment mark is considered to be opaque. At this time, the target alignment mark needs to cover the front layer alignment mark to avoid signal interference caused by the front layer alignment mark.
[0082] Specifically, when the diffraction light intensity of the alignment mark of the front layer is higher than the preset threshold, if the target alignment mark pattern is small and cannot cover the alignment mark of the front layer, the detection light emitted by the alignment system will be irradiated on the target alignment mark, and the target alignment mark and the alignment mark of the front layer will be diffracted at the same time. At this time, the pattern sensor of the alignment system will receive a messy light signal. Therefore, the target alignment mark needs to cover the alignment mark of the front layer.
[0083] The stacking direction of the multilayer film layers of the semiconductor structure is the first direction, and the plane perpendicular to the first direction is the first plane. When the target alignment mark covers the front layer alignment mark, the orthographic projection of the front layer alignment mark on the first plane is within the orthographic projection of the target alignment mark on the first plane.
[0084] At this time, as an example, the width of the orthographic projection of the target alignment mark on the first plane can be set to be greater than the width of the orthographic projection of the front layer alignment mark on the first plane, and / or the length of the orthographic projection of the target alignment mark on the first plane can be set to be greater than the length of the orthographic projection of the front layer alignment mark on the first plane.
[0085] At the same time, when setting the target alignment mark to cover the front layer alignment mark, the error between the target alignment mark and the front layer alignment mark in the actual process can be comprehensively considered so that the target alignment mark can completely cover the front layer alignment mark. For example, the front layer alignment mark is formed by a filling method, and the filling process may cause depression, etc., thereby affecting the size of the front layer alignment mark.
[0086] In step S430, a target alignment mark that blocks the front layer alignment mark designed in step S420 is prepared at a preset longitudinal position of the target film layer.
[0087] In this embodiment, when the diffraction light intensity of the current alignment mark is higher than a preset threshold, a target alignment mark is designed to block the previous alignment mark in the previous film layer, thereby effectively ensuring the alignment effect of the target alignment mark.
[0088] In one embodiment, after step S410, the following steps may also be included:
[0089] Step S42 , when the diffraction light intensity of the alignment mark of the current layer is lower than a preset threshold, a target alignment mark is formed on the target film layer at a preset longitudinal position.
[0090] When the diffraction light intensity of the front layer alignment mark is lower than the preset threshold, the front layer alignment mark is considered to be light-transmissive. At this time, the front layer alignment mark has little interference with the target alignment mark, and the target alignment mark can be directly prepared at the preset longitudinal position of the target film layer.
[0091] Specifically, when the diffraction light intensity of the front-layer alignment mark is lower than the preset threshold, the detection light emitted by the alignment system will pass through the front-layer alignment mark, the front-layer alignment mark generates less diffraction light, and the image sensor receives less messy light signals. At this time, the target alignment mark may not block the front-layer alignment mark in the front-layer film layer. Of course, it is understandable that in order to obtain a better alignment effect, the target alignment mark may also be set to block the front-layer alignment mark in the front-layer film layer.
[0092] As an example, when the material of the front-layer alignment mark is metal, the front-layer alignment mark can be considered opaque. When the material of the front-layer alignment mark is silicon dioxide or other materials, the front-layer alignment mark can be considered translucent.
[0093] In some cases, the film layer includes an alignment mark located in the cutting zone and a product structure located in the product zone. The alignment mark and the product structure may be formed simultaneously. In this case, obtaining the light transmittance information of the alignment mark may be equivalent to obtaining the light transmittance information of the corresponding product structure. Alternatively, in other cases, it may be considered that obtaining the light transmittance information of the alignment mark may be equivalent to obtaining the light transmittance information of the corresponding film layer.
[0094] It should be understood that although Figure 1The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.
[0095] Based on the same inventive concept, please refer to Figure 4 In one embodiment, a semiconductor structure 100 is provided, including a substrate 110 and a plurality of film layers stacked on the substrate 110 and provided with alignment marks. Among the film layers adjacent to the alignment marks, one close to the substrate 110 is used as a first film layer 120, and the other is used as a second film layer 130.
[0096] It can be understood that the first film layer 120 can be located between the second film layer 130 and the substrate 110 .
[0097] The semiconductor structure 100 includes a scribe line region and a product region. Figure 4 Only a part of the structure of the cutting road area is exemplarily shown in the figure. The first film layer 120 and the second film layer 130 are respectively provided with a first alignment mark 121 and a second alignment mark 131 in the cutting road area. The second alignment mark 131 is opaque.
[0098] Meanwhile, the first film layer 120 and the second film layer 130 may be provided with other structures in the product area.
[0099] The first film layer 120 is provided with a first alignment mark 121 at a preset longitudinal position, and the second film layer 130 is provided with a second alignment mark 131 at the same preset longitudinal position. It can be understood that both the first alignment mark 121 and the second alignment mark 131 can be located in the cutting path, and the second alignment mark 131 can be located above the first alignment mark 121.
[0100] Figures 5 to 10 The formation process of the first alignment mark 121 and the second alignment mark 131 is exemplarily shown. Figure 5 A first material film layer 12 is disposed on the substrate 110 in the cutting path, a first anti-reflection layer 140 is disposed on the first material film layer 12, and a first patterned photoresist layer 150 is disposed on the first anti-reflection layer 140. Figure 6, the first anti-reflection layer 140 is etched based on the first patterned photoresist layer 150 to form a first patterned anti-reflection layer 141, and then the first patterned photoresist layer 150 is removed.
[0101] See also Figure 7 , and then etching the first material film layer 12 based on the first patterned anti-reflection layer 141 , forming a first alignment mark 121 on the first material film layer 12 located in the cutting street area, and then removing the first patterned anti-reflection layer 141 .
[0102] As an example, the material of the substrate 110 may include semiconductor materials such as silicon, the material of the first material film layer 12 may include silicon dioxide, etc., and the material of the first anti-reflection layer 140 may include silicon oxynitride, etc.
[0103] See also Figure 8 After removing the first patterned photoresist layer 150 and the first patterned anti-reflection layer 141 and forming the first alignment mark 121, a material such as polysilicon may be used to cover the first alignment mark 121 to form a first dielectric layer 160. Next, a second dielectric material layer 17, a second anti-reflection layer 180, and a second patterned photoresist layer 190 are sequentially formed on the first dielectric layer 160. For example, the material of the second dielectric material layer 17 may be silicon nitride or the like.
[0104] See also Fig. 9 , the second anti-reflection layer 180 is etched based on the second patterned photoresist layer 190 to form a second patterned anti-reflection layer 181.
[0105] See also Fig.10 Then, based on the second patterned anti-reflection layer 181, the second dielectric material layer 17 is etched to form a plurality of grooves 200 in the second dielectric material layer 17. Then, the plurality of grooves 200 are filled to form a Figure 4 The remaining second dielectric material layer 17 forms a second dielectric layer 170.
[0106] When filling the plurality of grooves 200 to form the second alignment marks 131, a second material film layer may be first deposited on the entire surface. The material of the second material film layer is an opaque material. For example, the material of the second material film layer is a metal such as tungsten, copper or titanium.
[0107] Then, the second material film layer outside the groove 200 is removed by mechanical grinding or the like, and the second material film layer inside the groove 200 is retained to form an opaque second film layer 130. The second film layer 130 includes a second alignment mark 131 located in the cutting road area. For example, the second alignment mark 131 can be designed as a finer pattern to improve the uniformity of mechanical grinding.
[0108] Since the second film layer 130 is light-proof, the second alignment mark 131 is light-proof.
[0109] In this embodiment, the first film layer 120 is provided with a first alignment mark 121 at a preset longitudinal position, and the second film layer 130 is provided with a second alignment mark 131 at the same preset longitudinal position, so that the second alignment mark 131 is located directly above the first alignment mark 121, and the two can have the same longitudinal position without the need for misalignment preparation, thereby improving the utilization rate of the cutting path area. At the same time, the second alignment mark 131 is opaque, and when the alignment system detects the second alignment mark 131, the opaque layer makes the second alignment mark 131 not or not easily disturbed by the signal interference of the first alignment mark 121, thereby ensuring the alignment effect.
[0110] It can be understood that the first alignment mark 121 and the second alignment mark 131 are located in different film layers and have the same second direction coordinates and different first direction coordinates.
[0111] In one embodiment, the second alignment mark 131 covers the first alignment mark 121 .
[0112] The stacking direction of the first film layer and the second film layer is the first direction, and the plane perpendicular to the first direction is the first plane. When the second alignment mark 131 covers the first alignment mark 121, the orthographic projection of the first alignment mark 121 on the first plane is within the orthographic projection of the second alignment mark 131 on the first plane.
[0113] As an example, see Figure 4 , the first alignment mark 121 includes a plurality of first sub-patterns 1211. The second alignment mark 131 includes a plurality of second sub-patterns 1311. At this time, it can be known that the first sub-patterns 1211 and the second sub-patterns 1311 are arranged one by one, and the width X1 of the second sub-pattern 1311 can be greater than the width X2 of the first sub-pattern 1211. At this time, the second alignment mark 131 can cover the first alignment mark 121.
[0114] As an example, the first alignment mark 121 is also not transparent, so the first alignment mark 121 may cause signal interference during the alignment system detecting the second alignment mark 131. At this time, the second alignment mark 131 is set to cover the first alignment mark 121, so as to effectively prevent the first alignment mark 121 from interfering with the signal of the second alignment mark 131.
[0115] Of course, in some embodiments, when the first alignment mark 121 is light-transmissive, the second alignment mark 131 may be arranged to cover the first alignment mark 121 , so that the second alignment mark 131 may have a better calibration effect.
[0116] In addition, in this embodiment, the film layer includes an alignment mark located in the cutting area and a product structure located in the product area. The alignment mark is opaque, which can be equivalent to the corresponding product structure being opaque. Alternatively, the alignment mark is opaque, which can be equivalent to the corresponding film layer being opaque.
[0117] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features of the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0118] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.
Claims
1. A method for preparing an alignment mark, characterized in that: include: Acquire a target film layer, where the target film layer is a film layer on which an alignment mark is currently to be manufactured; When the target film layer is the first film layer that needs to be provided with an alignment mark, preparing a target alignment mark of the target film layer at a preset longitudinal position; When the target film layer is not the first film layer, obtaining light transmittance information of a target alignment mark of the target film layer; When the target alignment mark is opaque, the target alignment mark of the target film layer is prepared at the preset longitudinal position.
2. The method for preparing an alignment mark according to claim 1, characterized in that: When the target film layer is not the first film layer, before obtaining the light transmittance information of the target film layer, the method includes: Acquire alignment mark setting information of a front film layer, where the front film layer is a film layer obtained in a preceding process of the target film layer; When the front film layer is provided with a front alignment mark at a preset longitudinal position, light transmission information of the target alignment mark of the target film layer is obtained.
3. The method for preparing an alignment mark according to claim 2, characterized in that: When the front layer alignment mark is not provided at the preset longitudinal position of the front film layer, a target alignment mark of the target film layer is prepared at the preset longitudinal position.
4. The method for preparing an alignment mark according to claim 2, characterized in that: When the target alignment mark is opaque, preparing the target alignment mark of the target film layer at a preset longitudinal position includes: Acquiring the diffracted light intensity of the front layer alignment mark; When the diffraction light intensity of the front layer alignment mark is higher than a preset threshold, a target alignment mark is designed to cover the front layer alignment mark in the front film layer; A target alignment mark of the target film layer is prepared at a preset longitudinal position.
5. The method for preparing an alignment mark according to claim 4, characterized in that: When the diffraction light intensity of the front layer alignment mark is lower than a preset threshold, a target alignment mark is formed on the target film layer at the preset longitudinal position.
6. The method for preparing an alignment mark according to claim 1, characterized in that: When the target alignment mark is light-transmissive, the target alignment mark of the target film layer is prepared at a longitudinal position that is offset from a preset longitudinal position.
7. A semiconductor structure, characterized in that: It includes a substrate and a plurality of film layers stacked on the substrate and provided with alignment marks, wherein, among the film layers with adjacent alignment marks, one close to the substrate serves as a first film layer, and the other serves as a second film layer; the first film layer is provided with a first alignment mark at a preset longitudinal position; the second film layer is provided with a second alignment mark at the preset longitudinal position, and the second alignment mark is opaque.
8. The semiconductor structure according to claim 7, characterized in that: The second alignment mark covers the first alignment mark.
9. The semiconductor structure according to claim 8, characterized in that: The first alignment mark is opaque to light.
10. The semiconductor structure according to claim 8, characterized in that The first alignment mark includes a plurality of first sub-patterns, and the second alignment mark includes a plurality of second sub-patterns. The first sub-patterns are arranged opposite to the second sub-patterns, and the width of the second sub-patterns is greater than that of the first sub-patterns.