Overlay mark method, overlay measurement method, and overlay mark

Abstract

Embodiments of the present application disclose a kind of overlay mark method, overlay measurement method and overlay mark, wherein the overlay mark method includes: forming N first marks on the first material layer, each first mark includes P first sub-mark, the shape of the first sub-mark is the long strip shape formed by multiple block patterns;Form a second material layer after the first material layer;Form N second marks corresponding to each first mark on the second material layer, each second mark includes Q long strip second sub-mark;Wherein N, P and Q are all integers greater than 1, and P is greater than Q;Wherein the width of the first mark is greater than the width of the second mark.

Description

[0001] This application is a divisional application of Chinese patent application filed on January 2, 2020, with application number 202010003058.7 and invention title "A method for overlay marking, an overlay measurement method and an overlay marking". Technical Field

[0002] This application relates to the field of semiconductor devices and their manufacturing, and includes, but is not limited to, an overlay marking method, an overlay measurement method, and an overlay marking. Background Technology

[0003] In the manufacturing process of 3D NAND flash memory, to meet the high aspect ratio and high selectivity requirements of the gate line (GL) etching process, thicker and denser hard masks (HMs) are needed as conformal materials. However, as the material thickness and density increase, the absorption of light by these films also increases, while the reflection decreases, which greatly affects the photolithography process. In particular, it increases the difficulty of overlay measurement after photolithography, resulting in lower accuracy of OVL measurement of the developed pattern, affecting the OVL compensation results and thus the final yield level. Summary of the Invention

[0004] In view of this, embodiments of this application provide an overlay marking method, an overlay measurement method, and an overlay mark. By forming a first mark on a first material layer (such as a semiconductor substrate) and a second mark on a second material layer (polysilicon gate layer), the first mark and the second mark have different sizes and different compositions, which increases the contrast between the first mark and the second mark, thereby improving the accuracy of overlay measurement.

[0005] The technical solution of this application embodiment is implemented as follows:

[0006] This application provides a method for overlay marking, the method comprising:

[0007] N first marks are formed on the first material layer, each first mark including P first sub-marks, the shape of the first sub-mark being an elongated strip formed by multiple block-shaped patterns;

[0008] A second material layer is formed after the first material layer;

[0009] N second marks are formed on the second material layer, each corresponding to one of the first marks, and each second mark includes Q elongated second sub-marks;

[0010] Where N, P, and Q are all integers greater than 1, and P is greater than Q;

[0011] The width of the first mark is greater than the width of the second mark.

[0012] In some embodiments, forming N first marks on the first material layer includes:

[0013] On the first material layer, at least one first mark column is formed along a first direction and a second direction, respectively; wherein the first direction and the second direction are perpendicular.

[0014] Correspondingly, forming N second marks on the second material layer that correspond one-to-one with each of the first marks includes:

[0015] On the second material layer, at least one second mark column is formed along the first direction and the second direction, respectively; wherein, the first mark in the first mark column along the first direction and the second mark in the second mark column along the first direction correspond one-to-one, and the length direction of the first mark in the first mark column along the first direction and the length direction of the second mark in the second mark column along the first direction are perpendicular to the first direction; the first mark in the first mark column along the second direction and the second mark in the second mark column along the second direction correspond one-to-one, and the length direction of the first mark in the first mark column along the second direction and the length direction of the second mark in the second mark column along the second direction are perpendicular to the second direction.

[0016] In some embodiments, the number of markers in each marker column is equal, and when the first marker column and the second marker column are projected onto the same plane, the first marker column in the first direction is located inside the second marker column in the first direction, and the first marker column in the second direction is located inside the second marker column in the second direction.

[0017] In some embodiments, forming at least one first mark column on the first material layer along a first direction and a second direction respectively includes: forming two first mark columns on the first material layer along a first direction and a second direction respectively;

[0018] Correspondingly, on the second material layer, two second mark columns are formed along the first direction and the second direction, respectively, wherein the two mark columns in the same direction are centrally symmetrical.

[0019] In some embodiments, the width of the first marker is greater than the width of the second marker.

[0020] In some embodiments, the sum of the width of the first marker and the distance between two adjacent first markers is the first distance, and the sum of the width of the second marker and the distance between two adjacent second markers is the second distance;

[0021] Wherein, the first distance is equal to the second distance.

[0022] In some embodiments, the width of the first sub-tag is smaller than the width of the second sub-tag.

[0023] In some embodiments, the width of the second sub-marker is equal to the sum of the width of the first sub-marker and the distance between two adjacent first sub-markers.

[0024] In some embodiments, the distance between two adjacent first sub-markers is less than the distance between two adjacent second sub-markers.

[0025] In some embodiments, the first mark and the second mark are formed as grooves or protrusions.

[0026] This application provides a method for overlay measurement, the method comprising:

[0027] N first marks are formed on the first material layer, each first mark including P first sub-marks, the shape of the first sub-mark being an elongated strip formed by multiple block-shaped patterns;

[0028] A second material layer is formed after the first material layer;

[0029] N second marks are formed on the second material layer, each corresponding to one of the first marks. Each second mark includes Q elongated second sub-marks. N, P, and Q are all integers greater than 1, and P is greater than Q. The width of the first mark is greater than the width of the second mark.

[0030] Overlay measurement is performed based on the N first marks and the N second marks.

[0031] This application embodiment further provides an overlay mark, the mark comprising:

[0032] N first marks are formed on a first material layer, each first mark including P first sub-marks, the shape of the first sub-mark being an elongated strip formed by multiple block-shaped patterns;

[0033] N second marks are formed on the second material layer, and each second mark includes Q elongated second sub-marks;

[0034] There is a one-to-one correspondence between a first tag and a second tag, and N, P and Q are all integers greater than 1, with P being greater than Q;

[0035] The width of the first mark is greater than the width of the second mark.

[0036] The overlay marking method, overlay measurement method, and overlay marking provided in this application embodiment form a first mark on a first material layer and a second mark on a second material layer. The first mark and the second mark have different sizes, the first mark includes a different number of sub-marks, and the first mark and the second mark include a different composition. This increases the contrast between the first mark and the second mark, thereby improving the accuracy of overlay measurement. Attached Figure Description

[0037] In the accompanying drawings (which are not necessarily drawn to scale), similar reference numerals may describe similar parts in different views. The drawings illustrate, by way of example and not limitation, the various embodiments discussed herein.

[0038] Figure 1A This is a schematic diagram illustrating the relationship between film thickness and light transmittance in related technologies;

[0039] Figure 1B This is a schematic diagram of the structure of overlay marks in related technologies under an electron microscope;

[0040] Figure 1C This is a schematic diagram of the structure of overlay markings in related technologies;

[0041] Figure 1D This is a schematic diagram illustrating the dimensional relationship of the overlay marks in the current layer in the relevant technology;

[0042] Figure 1E A schematic diagram illustrating the symmetry of overlay mark measurement in related technologies;

[0043] Figure 2 A schematic flowchart illustrating the overlay marking method provided in an embodiment of this application;

[0044] Figure 3 This is a schematic diagram of the structure of the overlay mark provided in an embodiment of this application;

[0045] Figure 4 A flowchart illustrating an overlay marking method provided in this application embodiment;

[0046] Figure 5 This is a schematic diagram of the structure in which the overlay marks are projected onto the same plane, as provided in the embodiments of this application.

[0047] Figure 6 A schematic diagram illustrating the implementation process of the overlay measurement method provided in this application embodiment;

[0048] Figure 7 The linear relationship between ADI measurement results and AEI measurement results of the overlay marks provided in the embodiments of this application;

[0049] Figure 8The linear relationship between ADI measurement results and AEI measurement results of overlay marks provided in related technologies;

[0050] Figure 9 This is a schematic diagram illustrating the symmetry of overlay marking measurement provided in an embodiment of this application. Detailed Implementation

[0051] To make the technical solutions and advantages of the embodiments of this application clearer, the specific technical solutions of this application will be further described in detail below with reference to the accompanying drawings of the embodiments of this application. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0052] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0053] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0054] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0055] In detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure will be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0056] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0057] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0058] To better understand the marking method provided in the embodiments of this application, the problems in the related technologies are first analyzed and explained.

[0059] In the 3D NAND manufacturing process, to meet the high aspect ratio and high selectivity requirements of the GL Etch process, thicker and denser hard masks are needed as conformal materials. However, as the material thickness and density increase, the absorption of light by these films also increases, while the reflection decreases, which greatly affects the photolithography process. In particular, it makes OVL measurement after the photolithography process more difficult, and the accuracy of OVL measurement of the developed image is relatively low.

[0060] Figure 1A This is a schematic diagram illustrating the relationship between film thickness and transmittance in related technologies, such as... Figure 1A As shown in the figure, the transmittance of different HMs at different thicknesses was measured by a helium-neon laser with a wavelength of 633 nanometers (nm). It can be seen from the figure that the transmittance of the four different types of HMs gradually decreases as the thickness increases. Among them, APF, APFe, Kodiak, and Saphira™ are four different types of film layers.

[0061] Taking the symmetry measurement of Kodiak model AHM 390C 17K after photolithography as an example, Figure 1B This is a schematic diagram of an electron microscope structure marked during overlay measurement in related technologies, such as... Figure 1BAs shown, in the related technology, the marker 110 of the previous layer is relatively blurry under electron microscopy, while the marker 120 of the current layer can be seen clearly. Because the marker 110 of the previous layer is relatively blurry, the overlay measurement is inaccurate.

[0062] Figure 1C This is a schematic diagram of the structure of overlay markings in related technologies, such as... Figure 1C As shown, the overlay mark 120 of the current layer is set in the middle position, and the overlay mark 110 of the previous layer is set in the middle position. The sub-marks in the overlay mark 110 of the previous layer are perpendicular to the sub-marks in the overlay mark 120 of the current layer.

[0063] Figure 1D This is a schematic diagram illustrating the dimensional relationship of the overlay marks in the current layer in related technologies, such as... Figure 1D As shown, in the previous layer, one overlay mark includes two sub-markers. The distance between two adjacent overlay marks is 2400nm, the width of the two sub-markers is 250nm, and the distance between the sub-markers is 400nm.

[0064] Table 1 shows the dimensional relationship of the overlay marks in the previous layer in the related technology. As can be seen from Table 1, the pitch of the channel via segmentation (CH segmentation) is different, and the critical dimension (CD) is also different. The pitch and CD of the gate line segmentation (GL segmentation) are the same.

[0065] Overlay measurements are performed using the overlay marks of the previous layer and the overlay marks of the current layer.

[0066] Table 1. Relationship of Overlay Mark Dimensions in Related Technologies

[0067]

[0068] Figure 1E This is a schematic diagram of the symmetry after overlay measurement in related technologies, such as... Figure 1EAs shown, in the X direction, the mean is -0.04, the Raida criterion (3σ) is 5.76, and the absolute value of the mean plus the Raida criterion is 5.80. The minimum is -4.49, the maximum is 5.15, the median is -0.25, and the range is 9.64. In the Y direction, the mean is 0.25, the 3σ is 5.47, the absolute value of the mean plus the Raida criterion is 5.72, the minimum is -6.18, the maximum is 7.24, the median is 0.14, and the range is 13.42. Clearly, the symmetry deviations in both the X and Y directions are significant in the related technologies, and the symmetry is much higher when measured in units of 5 nm than when measured in units of 3 nm or less.

[0069] In related technologies, the accuracy of photolithographic overlay measurement with high light-absorbing films is very low, affecting OVL compensation results and thus the final yield level. Usually, to ensure the accuracy of photolithographic overlay measurement with high light-absorbing films, measurement must be performed after etching (AEI). However, since the etching has already taken place, it cannot be redone, which brings a large risk of scrap on the production line and is not conducive to mass production.

[0070] In view of the problems existing in related technologies, this application provides a method for overlay marking. Figure 2 This is a flowchart illustrating the overlay marking method provided in the embodiments of this application, as shown below. Figure 2 As shown, the method includes:

[0071] Step S201: Form N first marks on the first material layer.

[0072] Figure 3 This is a schematic diagram of the structure of the overlay mark provided in the embodiments of this application, such as... Figure 3 As shown, each first mark 320 includes P first sub-marks 321, and the shape of the first sub-mark 321 is an elongated shape formed by multiple block-shaped graphics.

[0073] In this embodiment, the first material layer may be an interconnect metal layer made of a metal such as aluminum or copper for fabricating metal wiring. It may also be a gate material layer made of a metal such as polysilicon or aluminum. In some embodiments, the first material layer may be an interlayer dielectric layer made of a low-dielectric-constant material such as silicon dioxide or black diamond (BD). In some embodiments, the first material layer may be a semiconductor substrate. For example, in the case of performing a photolithography process step to define an active region, a first mark 320 for overlay deviation inspection needs to be formed on the semiconductor substrate.

[0074] In this embodiment of the application, the formation of N first marks 320 on the first material layer can be achieved through the following steps:

[0075] In step S201A, a first photoresist layer is spin-coated onto the first material layer, and the pattern of N first marks 320 on the first mask is transferred onto the first photoresist layer by exposure and development to define the N first mark 320 pattern.

[0076] In this embodiment of the application, when the pattern of N first marks 320 on the first mask is transferred to the first photoresist layer by exposure and development, the circuit device structure pattern on the first mask is also transferred to the first photoresist layer covered by the first material layer.

[0077] In step S201B, using the first photoresist layer as a mask, the first material layer is etched to transfer the first mark 320 pattern on the first photoresist layer onto the first material layer, thereby forming N first marks 320 on the first material layer.

[0078] In this embodiment, a first photoresist displaying a circuit device structure pattern is used as a mask to etch the area outside the photoresist-covered area on the first material layer. After the etching process is completed, the circuit device structure pattern displayed on the first photoresist covering the first material layer is transferred to the first material layer, and simultaneously, N first markers 320 are also transferred to the first material layer.

[0079] Step S202: A second material layer is formed after the first material layer.

[0080] In this embodiment, the first material layer and the second material layer can be any two material layers on which patterns need to be formed through photolithography and etching processes during the entire semiconductor manufacturing process. Other dielectric thin film layers, conductive metal layers, etc., may also be deposited between the first material layer and the second material layer. For example, if the first material layer is a semiconductor substrate, the second material layer can be a stack composed of a polysilicon gate layer and a gate insulating layer.

[0081] In this embodiment of the application, the second material layer can be formed after the first material layer by a chemical vapor deposition (CVD) process or a plasma enhanced chemical vapor deposition (PECVD) process.

[0082] Step S203: N second marks 310 corresponding one-to-one with each of the first marks 320 are formed on the second material layer, wherein each second mark 310 includes Q elongated second sub-marks 311.

[0083] In this embodiment of the application, step S203 can be implemented through the following steps.

[0084] In step S203A, a second photoresist layer is spin-coated onto the second material layer, and the pattern of N second marks 310 on the second mask is transferred to the second photoresist layer by exposure and development to define the N second mark 310 pattern.

[0085] In step S203B, using the second photoresist layer as a mask, the second material layer is etched to transfer the second mark 310 pattern on the second photoresist layer onto the second material layer, thereby forming N second marks 310 on the second material layer.

[0086] In this embodiment of the application, the second marker 310 can be implemented in the same way as the first marker 320, and will not be described again here.

[0087] Continue to refer to Figure 3 When the first mark column and the second mark column are projected onto the same plane, the first mark and the second mark are in one-to-one correspondence, and the width of the first mark 320 is greater than the width of the second mark 310.

[0088] In this embodiment, by setting P greater than Q, and the first sub-marker 321 being a long strip formed by multiple block-shaped graphics, each second mark 310 includes Q long strip-shaped second sub-markers 311, increasing the alignment points for overlay. Furthermore, by setting the width of the first mark 320 greater than the width of the second mark 310, the contrast between the first mark 320 and the second mark 310 is increased. For example, P is 6 and Q is 4.

[0089] In the embodiments of this application, N, P, and Q are all integers greater than 1.

[0090] In this embodiment, since layer alignment, or overlay alignment, is required during photolithography to ensure alignment between the pattern on the second material layer and the existing pattern on the first material layer, a high overlay accuracy is desired to achieve good product performance and high yield. Specifically, overlay accuracy refers to the alignment accuracy between the pattern on the surface of the first material layer and the pattern on the photomask of the second material layer.

[0091] In this embodiment, the relative size relationship between the first mark and the second mark and the square block structure can be set by those skilled in the art according to actual needs, and this specific embodiment does not limit this.

[0092] In this embodiment, a first mark 320 is formed on a first material layer (previous layer), and a second mark 310 is formed on a second material layer (current layer). The size of the first mark 320 is larger than the size of the second mark, and the number of first sub-marks 321 included in the first mark 320 is greater than the number of second sub-marks 311 included in the second mark 310. The different compositions of the first sub-marks 321 and the second sub-marks 311 increase the contrast between the first mark 320 and the second mark 310, thereby improving the accuracy of overlay measurement. The overlay marking method provided in this embodiment can achieve accurate measurement of OVL after development, which is beneficial for online OVL control and eliminates the risk of AEI OVL scrap.

[0093] This application provides another method for overlay marking. Figure 4 A flowchart of an overlay marking method provided in an embodiment of this application is shown below. Figure 4 As shown, the method includes:

[0094] Step S401: On the first material layer, at least one first mark column is formed along the first direction and the second direction, respectively.

[0095] Continue to refer to Figure 3 The first direction is perpendicular to the second direction. In this embodiment, at least one first marker column consists of a plurality of first markers 320, and the first markers 320 in a marker column are parallel to each other. The first direction can be considered to be along the X direction, and the second direction is along the Y direction.

[0096] For example, two first mark columns are formed on the first material layer along a first direction and a second direction, respectively.

[0097] Step S402: A second material layer is formed after the first material layer.

[0098] Step S402: On the second material layer, at least one second mark column is formed along the first direction and the second direction, respectively.

[0099] In this embodiment of the application, the at least one second marker column is composed of a plurality of second markers 310, and the second markers 310 in a second marker column are parallel to each other.

[0100] For example, two first mark columns are formed on the second material layer along the first direction and the second direction, respectively.

[0101] In this embodiment, the first mark 320 in the first mark column along the first direction and the second mark 310 in the second mark column along the first direction correspond one-to-one, and the length directions of the first mark 320 in the first mark column along the first direction and the second mark 310 in the second mark column along the first direction are perpendicular to the first direction; the first mark 320 in the first mark column along the second direction and the second mark 310 in the second mark column along the second direction correspond one-to-one, and the length directions of the first mark 320 in the first mark column along the second direction and the second mark 310 in the second mark column along the second direction are perpendicular to the second direction.

[0102] Figure 5 This is a schematic diagram of the structure in which the overlay marks are projected onto the same plane, as shown in the embodiments of this application. Figure 5 As shown, the number of first and second marks in each mark column is equal. When the first mark column 510 and the second mark column 520 are projected onto the same plane, the first mark column 510 in the first direction is located inside the second mark column 520 in the first direction, and similarly, the first mark column 510 in the second direction is located inside the second mark column 520 in the second direction.

[0103] The method provided in this application reduces measurement interference caused by previous processes (such as chemical mechanical polishing, CMP) by placing a first mark inside a marking measurement area and a second mark outside the marking measurement area. Using the overlay marking method provided in this embodiment, after-development inspection (ADI) can be achieved in the presence of an HM layer, allowing measurement to be performed before the etching process and avoiding the defects of irreversible rework and uncontrollable overlay compensation.

[0104] In some embodiments, the width of the first marker is greater than the width of the second marker.

[0105] In this embodiment of the application, the width of the first mark and the width of the second mark can be set according to the actual situation.

[0106] For example, the width of the first marker is 1310 nm and the width of the second marker is 1190 nm.

[0107] In some embodiments, the sum of the width of the first marker and the distance between two adjacent first markers is the first distance, and the sum of the width of the second marker and the distance between two adjacent second markers is the second distance;

[0108] Wherein, the first distance is equal to the second distance.

[0109] Continuing with the example above, the distance between two adjacent first markers is 690 nm, and the distance between two adjacent second markers is 810 nm. Both the first and second distances are 2000 nm.

[0110] In some embodiments, the width of the first sub-tag is smaller than the width of the second sub-tag.

[0111] Continuing with the example above, the width of the first sub-tag is 240nm, and the width of the second sub-tag is 350nm.

[0112] In some embodiments, the width of the second sub-marker is equal to the sum of the width of the first sub-marker and the distance between two adjacent first sub-markers.

[0113] Continuing with the example above, the distance between two adjacent first sub-markers is 110nm.

[0114] In some embodiments, the distance between two adjacent first sub-markers is less than the distance between two adjacent second sub-markers.

[0115] Continuing with the example above, the distance between two adjacent second markers is 140nm.

[0116] In some embodiments, the first mark and the second mark are formed as grooves or protrusions.

[0117] In this embodiment of the application, setting the first mark and the second mark to be grooved or raised can increase the contrast between the first mark and the second mark.

[0118] For example, the first mark is set in a groove shape, and the second mark is set in a raised shape.

[0119] Based on the foregoing embodiments, Figure 6 This is a schematic diagram illustrating the implementation process of the overlay measurement method provided in the embodiments of this application, as shown below. Figure 6 As shown, the method includes:

[0120] Step S601: N first marks are formed on the first material layer, each first mark including P first sub-marks, the shape of the first sub-mark being a strip formed by multiple block-shaped patterns;

[0121] Step S602: N second marks are formed on the second material layer, each corresponding to one of the first marks. Each second mark includes Q elongated second sub-marks. N, P, and Q are all integers greater than 1, and P is greater than Q. The width of the first mark is greater than the width of the second mark.

[0122] Step S603: Perform overlay measurement based on the N first marks and the N second marks.

[0123] In this embodiment of the application, during the overprinting alignment operation, a measuring device is used to measure the first mark on the first material layer and the second mark on the second material layer to determine the overprinting deviation between the second material layer and the first material layer. Specifically, the measuring device obtains the overprinting mark positions on the second material layer and the first material layer by measurement, and determines the overprinting deviation between the second material layer and the first material layer by calculating the difference between the corresponding overprinting mark positions on the second material layer and the first material layer.

[0124] Exemplarily, a specific overlay mark is obtained using the overlay marking method provided in the embodiments of this application, wherein the overlay mark provided in the embodiments of this application is as follows: Figure 3 As shown in Table 2, the dimensional relationship of the overlay marks is illustrated. Table 2 shows that the current layer (the second material layer in this application) and the previous layer (the second material layer in this embodiment) both have four mark columns in the X and Y directions. Each layer's four marks are within a 30mm*30mm target size. In the current layer, the pitch between the first marks is 2000nm, the CD is 1190nm, the segmentation pitch is 350nm, and the CD is 140nm. The first mark has a para structure. In the previous layer, the pitch between the second marks is 2000nm, the CD is 1310nm, the segmentation pitch is 240nm, and the CD is 140nm. The second mark has a hole structure. The first mark contains six first sub-marks, and the second mark contains four second sub-marks.

[0125] Table 2. Size relationship of the overlay marks provided in the embodiments of this application.

[0126]

[0127] The first and second marks were measured by ADI and AEI to obtain the measurement results. Figure 7 The linear relationship between the ADI measurement results and AEI measurement results of the overlay markings provided in this application embodiment is shown. Where y = 0.8753x + 0.0283, R... 2 =0.9348, R2 Approximately equal to 0.93, where y represents the value of the vertical axis and x represents the value of the horizontal axis. Measurement data after etching is represented by a straight line, and measurement data after development is represented by dots.

[0128] Using the overlay marks provided in related technologies as a reference, ADI and AEI measurements were performed. The specific overlay marks in the related technologies are detailed in Table 1. Figure 8 The linear relationship between the ADI measurement results and AEI measurement results of the marker provided in the related technology is given, where y = 0.7748x - 0.5474, R 2 =0.8078, R 2 Approximately equal to 0.81, y represents the value of the vertical axis, and x represents the value of the horizontal axis. Measurement data after etching is represented by a straight line, and measurement data after development is represented by dots.

[0129] Through the Figure 7 and Figure 8 The comparison, Figure 7 The dots in the image tend to cluster more near the straight lines, while Figure 8 The dots are scattered near the straight line. Obviously, the markings formed by the marking method provided in this application have a high correlation with the original data of AEI measurement and ADI measurement under electron microscope scanning.

[0130] Figure 9 This is a schematic diagram illustrating the symmetry measurement method provided in the embodiments of this application, such as... Figure 9 As shown, in the X direction, the mean is -0.12, the 3Sigma is 1.51, and the absolute value of the mean according to the Galida criterion is 1.64. The min is -2.98, the max is 2.25, the median is -0.02, and the range is 5.23. In the Y direction, the mean is 0.04, the 3Sigma is 2.02, the absolute value of the mean according to the Galida criterion is 2.06, the min is -2.57, the max is 2.91, the median is -0.02, and the range is 5.48. (Comparison) Figure 9 and Figure 1E Obviously, the measurement results of the overlay markings formed by the overlay marking method provided in this application embodiment have better symmetry.

[0131] For any technical details not disclosed in the embodiments of the overlay measurement method of this application, please refer to the description of the marking method embodiments of this application for understanding.

[0132] Based on the foregoing embodiments, this application provides an overlay mark, the overlay mark comprising:

[0133] N first marks are formed on a first material layer, each first mark including P first sub-marks, the shape of the first sub-mark being an elongated strip formed by multiple block-shaped patterns;

[0134] N second marks are formed on the second material layer, and each second mark includes Q elongated second sub-marks;

[0135] There is a one-to-one correspondence between a first tag and a second tag, and N, P and Q are all integers greater than 1, with P being greater than Q;

[0136] The width of the first mark is greater than the width of the second mark.

[0137] It should be noted that the description of the markings in this embodiment is similar to the description of the overlay marking method in the above method embodiments, and has similar beneficial effects as the method embodiments, therefore, it will not be described again. For technical details not disclosed in the interconnect structure embodiments of this application, please refer to the description of the above method embodiments of this application for understanding.

[0138] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0139] Equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A lithography mark, characterized in that, The application relates to a set of overlay marks, comprising: at least one first mark column arranged along a first direction and a second direction respectively, the first mark column comprising N first marks, each of the first marks comprising a plurality of first sub-marks in a strip shape formed by a plurality of block patterns; wherein the first direction and the second direction are perpendicular; and the N is an integer greater than 1; at least one second mark column arranged along the first direction and the second direction respectively, the second mark column comprising N second marks corresponding to each of the first marks, each of the second marks comprising a plurality of second sub-marks in a strip shape; and the number of the first sub-marks in the first mark is different from the number of the second sub-marks in the second mark; wherein the first mark column is arranged on a first material layer, the second mark column is arranged on a second material layer, and the second material layer is above the first material layer; the first mark column along the first direction is inside the orthographic projection of the second mark column along the first direction on the first material layer, the first mark column along the second direction is inside the orthographic projection of the second mark column along the second direction on the first material layer, the orthographic projection of the first mark column and the second mark column on the first material layer forms an integral mark structure, and the inside is a position close to the center point of the integral mark structure.

2. The overlay marks according to claim 1, wherein: the first marks in the first mark column along the first direction are arranged along the first direction, and the extension direction of the first marks in the first mark column along the first direction is perpendicular to the first direction; the second marks in the second mark column along the first direction are arranged along the first direction, and the extension direction of the second marks in the second mark column along the first direction is perpendicular to the first direction; the first marks in the first mark column along the second direction are arranged along the second direction, and the extension direction of the first marks in the first mark column along the second direction is perpendicular to the second direction; the second marks in the second mark column along the second direction are arranged along the second direction, and the extension direction of the second marks in the second mark column along the second direction is perpendicular to the second direction.

3. The overlay marks according to claim 1, wherein: in the first marks in the first mark column along the first direction, the width of the first mark along the first direction and the distance between adjacent two first marks are equal to a first distance, and in the second marks in the second mark column along the first direction, the width of the second mark along the first direction and the distance between adjacent two second marks are equal to a second distance; wherein the first distance is equal to the second distance. In the first marks in the first mark column along the second direction, a width of the first mark along the second direction and a distance between two adjacent first marks are a third distance; in the second marks in the second mark column along the second direction, a width of the second mark along the second direction and a distance between two adjacent second marks are a fourth distance; wherein the third distance is equal to the fourth distance.

4. The overlay mark of claim 1, wherein, The first mark and the second mark include a groove shape or a protrusion shape.

5. The overlay mark of claim 1, wherein, The width of the first sub-mark is smaller than the width of the second sub-mark.

6. The overlay mark of claim 1, wherein, The width of the second sub-mark is equal to the sum of the width of the first sub-mark and the distance between two adjacent first sub-marks.

7. The overlay mark of claim 1, wherein, The overlay mark includes: Two first mark columns respectively arranged along the first direction and the second direction; two second mark columns respectively arranged along the first direction and the second direction; wherein the two first mark columns along the same direction and the two second mark columns along the same direction are centrosymmetric.

8. A mark for overlay, characterized in that Comprise: On the first material layer, at least one first mark column is formed along the first direction and the second direction respectively, the first mark column comprises N first marks, each first mark comprises a plurality of first sub-marks, the shape of the first sub-mark is a long strip formed by a plurality of block patterns; wherein the first direction and the second direction are perpendicular; the N is an integer greater than 1; Form a second material layer on the first material layer; On the second material layer, at least one second mark column is formed along the first direction and the second direction respectively, the second mark column comprises N second marks corresponding to each first mark, each second mark comprises a plurality of long strip-shaped second sub-marks; the number of first sub-marks included in the first mark is different from the number of second sub-marks included in the second mark; Wherein, the first mark column along the first direction is located on the inner side of the orthographic projection of the second mark column along the first direction on the first material layer, the first mark column along the second direction is located on the inner side of the orthographic projection of the second mark column along the second direction on the first material layer, the orthographic projection of the first mark column and the second mark column on the first material layer constitutes an integral mark structure, and the inner side is close to the center point of the integral mark structure.

9. A method of overlay measurement, the method comprising: Comprise: On the first material layer, at least one first mark column is formed along the first direction and the second direction respectively, the first mark column comprises N first marks arranged along the first direction or the second direction, each first mark comprises a plurality of first sub-marks, the shape of the first sub-mark is a long strip formed by a plurality of block patterns; wherein the first direction and the second direction are perpendicular; the N is an integer greater than 1; Form a second material layer on the first material layer; On the second material layer, at least one second mark column is formed along the first direction and the second direction respectively, the second mark column comprises N second marks corresponding to each of the first marks, each of the second marks comprises a plurality of long strip-shaped second sub-marks; the number of first sub-marks comprised by the first marks is different from the number of second sub-marks comprised by the second marks; wherein the first mark column along the first direction is located at the inner side of the orthographic projection of the second mark column along the first direction on the first material layer, the first mark column along the second direction is located at the inner side of the orthographic projection of the second mark column along the second direction on the first material layer, the orthographic projection of the first mark column and the second mark column on the first material layer constitutes an integral mark structure, and the inner side is a position close to the center point of the integral mark structure; According to the N first marks and the N second marks, overlay measurement is performed.

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