Lithographic alignment marks and their adaptive design method, device and alignment method

Abstract

The present invention discloses a lithography alignment mark, an adaptive design method, a device and an alignment method thereof. The adaptive design method includes: analyzing based on preset layout design rules and process requirements to obtain an analysis result, where the analysis result includes at least one or more of the following: graphic shape, graphic size, and graphic density; determining the lithography alignment mark according to the analysis result. The alignment method includes: placing two groups of lithography alignment marks on the TSV layer layout, the two groups of lithography alignment marks being mirror images along the Y-axis, one group being used for automatic alignment of the front-illumination lithography layer, and the other group being used for automatic alignment of the back-illumination lithography layer after bonding. Based on the preset layout design rules and process requirements, the present invention adaptively designs the graphic shape, graphic size, and graphic density of the lithography alignment mark, solves the problem of incompatibility between the alignment mark and the special process, and uses the lithography alignment mark to achieve full-automatic alignment in the TSV process, improving graphic resolution, alignment accuracy, and production yield.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and particularly to a lithography alignment mark, an adaptive design method and device thereof, and an alignment method. Background Art

[0002] The lithography process is an important step in patterning during semiconductor manufacturing. Especially in large-scale integrated circuits, usually dozens of lithography processes need to be performed on a wafer to achieve the three-dimensional stacking of different device structures in the integrated circuit. The positional relationship between different lithography layers is represented by the overlay accuracy, which is an important parameter to ensure the chip performance. With the further development of the lithography process, higher requirements are put forward for the overlay accuracy. Therefore, lithography machine manufacturers have all launched automated alignment systems and provided standard alignment marks to achieve more accurate and faster automatic alignment lithography processes.

[0003] Taking the ASML lithography machine as an example, it is equipped with an automatic alignment system of TTL (Through The Lens, coaxial alignment) and OA (Off-Axis illumination, off-axis illumination), and at the same time provides a series of standard alignment marks, such as Figure 1 As shown, it is the standard SPM X-mark alignment mark provided by ASML. This alignment mark needs to be used in pairs with X / Y-mark. Figure 1 What is shown in the figure is the X-mark. Rotating the X-mark counterclockwise by 90° can obtain the Y-mark. The column length in the figure is 72 μm. In the figure, pitch represents the period between columns of the alignment mark, which is the sum of the widths of a black graphic area and the adjacent blank area. pitch16 represents that the period between columns is 16 μm, and pitch17.6 represents that the period between columns is 17.6 μm. These alignment marks have fixed shapes, sizes and fixed periods, can achieve automatic alignment, and obtain higher overlay accuracy. For I-line machines, an overlay accuracy of less than 50 nm can be obtained, and for KrF and ArF lithography machines, an overlay accuracy of less than 10 nm can be obtained.

[0004] However, for special processes such as CMP (Chemical Mechanical Polishing), copper electroplating, and deep etching, there are requirements for the shape, size, density, etc. of the designed patterns in the layout. The size of the alignment marks provided by lithography machine manufacturers is often much larger than the designed patterns, making it impossible to be compatible with the process, and it is easy to produce defects such as dishing (surface depression) and void (hole) at the alignment marks. In particular, for the TSV (Through-Silicon-via) process, only round holes of the same size are allowed to appear in the TSV layer layout, and no other shapes and sizes of patterns are allowed. The reason is that if the size of the pattern is smaller than the pattern with the TSV diameter, due to the too small opening, during the copper electroplating process, the hole is closed in advance before being filled with copper, and during the thermal annealing process, the gas in the hollow hole expands to generate a bulge, resulting in the scrapping of the wafer; while a too large pattern will obtain a greater etching depth. When thinning after bonding, the deeper pattern area will expose copper in advance, hindering the continuation of thinning, thus resulting in the abnormal exposure of copper for the TSV pattern. Therefore, in the TSV process, especially in the back-illumination process after the backside of the TSV exposes copper, it is impossible to use the alignment marks provided by lithography machine manufacturers to achieve automatic alignment and lithography operations on a projection lithography machine.

[0005] Regarding the problem that the TSV process cannot be compatible with the alignment marks of the lithography machine, the current solutions are as follows: 1. Perform lithography and etching of the zero-layer alignment marks on a projection lithography machine to obtain alignment marks on the wafer for subsequent front-illumination processes; 2. Automatically align the front-illumination lithography layers such as the TSV layer and the Top metal (top metal layer) with the zero-layer alignment marks, and complete the front-illumination lithography and other processes on a projection lithography machine; 3. After bonding and thinning to expose the backside of the TSV with copper, use the manual alignment method to perform back-illumination lithography and other processes on a 1:1 contact lithography machine. However, the above solutions have the following defects: First, performing lithography and etching of the zero-layer alignment marks increases the process steps of one lithography and etching, increasing the manufacturing cost; Second, using the manual alignment method to perform back-illumination lithography on a 1:1 contact lithography machine not only has low pattern resolution, poor alignment accuracy, and the overlay accuracy is usually at the micron level, but also has high requirements for operators, is prone to errors, and has low production. Summary of the Invention

[0006] In view of this, embodiments of the present invention provide a lithography alignment mark, an adaptive design method, a device, and an alignment method thereof to solve the problem of incompatibility between the alignment mark and the special process, so that the lithography alignment mark formed by adaptive design simultaneously matches the special process requirements and the lithography machine alignment requirements, realizing automatic alignment while avoiding defects at the alignment mark.

[0007] To this end, embodiments of the present invention provide the following technical solutions:

[0008] The first aspect of the present invention provides a method for adaptive design of lithography alignment marks, including:

[0009] Analyze based on preset layout design rules and process requirements to obtain an analysis result, where the analysis result includes at least one or more of the following: graphic shape, graphic size, and graphic density; determine the lithography alignment marks according to the analysis result.

[0010] Optionally, determining the lithography alignment marks according to the analysis result specifically includes: dividing each column of the original alignment marks according to the analysis result, and making the period between columns of the divided lithography alignment marks the same as or an integer multiple of the period between columns of the original alignment marks.

[0011] Optionally, the graphic shape is one of a rectangle, a square, a rounded rectangle, and a circle.

[0012] Optionally, the graphic size is 1 - 72 μm.

[0013] Optionally, the graphic density includes the proportion of graphics in each column and the proportion of columns in each period.

[0014] Optionally, the proportion of graphics in each column is 0.2 - 1, and the proportion of columns in each period is 0.2 - 0.8.

[0015] The second aspect of the present invention provides a device for adaptive design of lithography alignment marks, including:

[0016] An analysis module for analyzing based on preset layout design rules and process requirements to obtain an analysis result, where the analysis result includes at least one or more of the following: graphic shape, graphic size, and graphic density;

[0017] A lithography alignment mark determination module for determining the lithography alignment marks according to the analysis result.

[0018] Optionally, the lithography alignment mark determination module includes a splitting module for splitting each column of the original alignment marks according to the analysis result, and making the period between columns of the split lithography alignment marks the same as or an integer multiple of the period between columns of the original alignment marks.

[0019] The third aspect of the present invention provides a lithography alignment mark formed by using the method for adaptive design of lithography alignment marks according to the first aspect of the present invention.

[0020] The fourth aspect of the present invention provides an alignment method, including:

[0021] Place two sets of the lithography alignment marks described in the third aspect of the present invention on the TSV layer layout, and the two sets of the lithography alignment marks are mirror-symmetrical along the Y axis;

[0022] Prepare a wafer, and perform TSV layer lithography, etching, copper electroplating, and CMP;

[0023] Perform front-side lithography layer lithography and automatically align with one set of the lithography alignment marks on the TSV layer;

[0024] Bond and thin the wafer to expose the copper on the back side of the TSV and the back sides of the two sets of the lithography alignment marks;

[0025] Perform back-side lithography layer lithography and automatically align with the other set of the lithography alignment marks on the TSV layer.

[0026] The technical solution of the embodiment of the present invention has the following advantages:

[0027] The embodiment of the present invention provides a lithography alignment mark, an adaptive design method, a device, and an alignment method thereof. Based on preset layout design rules and process requirements, the graphic shape, graphic size, and graphic density of the lithography alignment mark are adaptively designed, and the problem of incompatibility between the alignment mark and a special process is solved. Two sets of the lithography alignment marks are placed on the TSV layer, one set is placed normally, and the other set is placed after being mirrored along the Y axis, so as to realize full-automatic alignment of the TSV process, avoid generating defects at the alignment mark at the same time, can eliminate the zero-layer alignment mark, simplify the process flow, and improve the graphic resolution, alignment accuracy, and yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 is the standard SPM X-mark alignment mark provided for ASML manufacturers;

[0030] Figure 2 is the flowchart of the adaptive design method of the lithography alignment mark according to the embodiment of the present invention;

[0031] Figure 3 is the structural block diagram of the adaptive design device of the lithography alignment mark according to the embodiment of the present invention;

[0032] Figure 4a is the lithography alignment mark formed by the adaptive design method of the lithography alignment mark according to an embodiment of the present invention;

[0033] Figure 4b is a lithography alignment mark formed by the lithography alignment mark adaptive design method according to an embodiment of the present invention;

[0034] Figure 4c is a lithography alignment mark formed by the lithography alignment mark adaptive design method according to an embodiment of the present invention;

[0035] Figure 5 is a lithography alignment mark formed by the lithography alignment mark adaptive design method according to another embodiment of the present invention;

[0036] Figure 6 is a flowchart of the alignment method according to an embodiment of the present invention. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0038] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0039] In this application, the term "exemplary" is used to mean "serving as an example, illustration, or explanation". Any embodiment described as "exemplary" in this application is not necessarily to be construed as more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. In the following description, details are set forth for the purpose of explanation. It should be understood that those of ordinary skill in the art can recognize that this application can be implemented without these specific details. In other instances, well-known structures and processes are not elaborated in detail so as not to obscure the description of this application with unnecessary details. Therefore, this application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0040] According to an embodiment of the present invention, an embodiment of a lithography alignment mark adaptive design method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0041] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] In this embodiment, a lithography alignment mark adaptive design method is provided. Figure 2 is a flowchart of a lithography alignment mark adaptive design method according to an embodiment of the present invention, as Figure 2 shown, the process includes the following steps:

[0043] S1. Analyze based on preset layout design rules and process requirements to obtain an analysis result, and the analysis result includes at least one or more of the following: graphic shape, graphic size, and graphic density. Since the graphic shape, graphic size, and graphic density are all important information for layout graphic design, usually the analysis result includes the graphic shape, graphic size, and graphic density at the same time.

[0044] The layout design rules of this embodiment are for the TSV process. Therefore, the layout design rules include the silicon via graphic shape, diameter, and the silicon via graphic density in the dense area of the layout. The process requirements refer to subsequent alignment and other process requirements, such as deep etching, copper plating, CMP and other process requirements, as well as the alignment requirements of the lithography machine.

[0045] S2. Determine the lithography alignment marks according to the analysis results. Specifically, each column of the original alignment marks is segmented according to the analysis results, and the period between columns of the segmented lithography alignment marks is the same as or an integer multiple of the period between columns of the original alignment marks. The graphic shape and size of the lithography alignment marks obtained after segmentation are consistent with the shape and size of the silicon vias in the layout, and the graphic density of the lithography alignment marks is consistent with the silicon via graphic density in the dense area of the preset layout.

[0046] In this embodiment, without changing the period between columns of the original alignment marks, each column of the original alignment marks is segmented according to the analysis results, so that the segmented graphics are evenly distributed on the center line of the original alignment marks without changing the period between the original columns, which is convenient for subsequent automatic alignment and simplifies the process flow. The period between columns of the lithography alignment marks obtained after segmentation can also be an integer multiple of the period between columns of the original alignment marks, such as 2 times, 3 times, etc., and the segmented graphics can also be evenly distributed on the center line of a certain column of the original alignment marks. In this embodiment, the original alignment marks refer to the standard alignment marks provided by the lithography machine during the subsequent alignment process.

[0047] In this embodiment, the graphic shape is one of a rectangle, a square, a rounded rectangle, and a circle. When the graphic shape is a rectangle or a rounded rectangle, the graphic size refers to the width of the rectangle or the rounded rectangle. When the graphic shape is a square, the graphic size refers to the side length of the square; when the graphic shape is a circle, the graphic size refers to the diameter of the circle. The graphic size is 1 - 72 μm, so that the lithography alignment marks are compatible with the design graphics in the preset layout, and the maximum graphic size does not exceed the column length of the original alignment marks, that is, there is at least one complete graphic in each column.

[0048] The pattern density in this embodiment includes the pattern proportion in each column and the column proportion within each period. The pattern proportion in each column represents the pattern density in the Y direction. It is the ratio of a pattern area to the sum of the pattern and its adjacent blank areas in the same column. The adjacent blank areas selected are the blank areas between two patterns. If there are incomplete patterns or incomplete blank areas when approaching the edge of the pattern column, the incomplete patterns and incomplete blank areas are discarded and ignored. The column proportion within each period represents the pattern density in the X direction. It is the ratio of a pattern column to the sum of the column and its adjacent blank areas within one period (pitch), that is, within one period, the ratio of a column to the sum of the column and its adjacent blank areas. The adjacent blank areas selected are the blank areas between two columns. If there are incomplete columns or incomplete blank areas when approaching the edge of the mark, the incomplete columns and incomplete blank areas are discarded and ignored. When the period of the mark changes to an integer multiple of the original mark period, it may cause a difference in the total length of the new pattern from the original pattern. The number of patterns can be adjusted according to the actual situation to ensure that the total length of the mark is between 650 - 727 μm.

[0049] The pattern proportion in each column is 0.2 - 1, and there is at least one complete pattern in each column, and there may be no blank areas; the column proportion within each period is 0.2 - 0.8, and the gaps between columns are reserved to make the lithography alignment marks compatible with the designed pattern density in the preset layout. Too small a pattern density will reduce the alignment signal intensity; while too large a pattern density may cause process abnormalities such as deep etching, copper electroplating, and CMP. In particular, for the TSV process, the pattern shape, pattern size, and pattern density of the lithography alignment marks should be consistent with those of the TSV layer layout design.

[0050] This embodiment adaptively designs the lithography alignment marks according to the design rules of the layout patterns and process requirements, avoiding defects such as dishing and void at the alignment marks during the alignment process.

[0051] In this embodiment, a device for adaptive design of lithography alignment marks is also provided. This device is used to implement the above - mentioned embodiment, and those that have been described will not be repeated. As used hereinafter, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0052] Figure 3 It is a structural block diagram of a device for adaptive design of lithography alignment marks according to an embodiment of the present invention; as Figure 3 shown, it includes:

[0053] Analysis module 1 is used to perform analysis based on preset layout design rules and process requirements to obtain analysis results, and the analysis results at least include one or more of the following: graphic shape, graphic size, and graphic density. The analysis module 1 can obtain the analysis results by using methods such as stroking, as long as the analysis results can be obtained, and no special limitation is made here.

[0054] Lithography alignment mark determination module 2 is used to determine the lithography alignment marks according to the analysis results.

[0055] The lithography alignment mark determination module 2 further includes a splitting module 20, which is used to split each column of the original alignment marks according to the analysis results, and make the period of the split lithography alignment mark columns the same as or an integer multiple of the period of the original alignment mark columns.

[0056] The further function descriptions of the above-mentioned various modules are the same as those in the corresponding embodiments above, and will not be elaborated here.

[0057] An embodiment of the present invention also provides a lithography alignment mark formed by using the above Figure 2 shown lithography alignment mark adaptive design method.

[0058] Please refer to Figures 4a - 4c , Figure 4a shown is a lithography alignment mark formed by splitting a variety of graphic shapes, graphic sizes, and graphic densities based on the SPM X-mark alignment mark. On the premise of keeping the period of column to column unchanged, each column of the original SPM X-mark alignment mark is respectively split into 8*8μm square, 8μm diameter circle, and 8*4μm rectangle. The graphic proportion in each column of the three split marks is 0.5. When splitting the columns according to the described scheme, first, after making the sum of the maximum integer number of graphics arranged in the column direction and its adjacent blank area, if the remaining size is greater than or equal to the single graphic size, add one more graphic; if the remaining size is less than the single graphic size, delete the incomplete graphic. Figure 4a In the first two splitting schemes, the sum of the graphic and its adjacent blank area is 16μm, 4 complete periods are placed, the total size is 64μm, and the remaining 8μm is equal to the single graphic size, so one more graphic is added; Figure 4aIn the last segmentation scheme, the sum of the figure and its adjacent blank area is 8 μm. Nine complete cycles are placed, and the total size is 72 μm. The column occupancy ratio in each cycle to the left of the centers of the three marked centers after segmentation is 0.5, and the column occupancy ratio in each cycle to the right of the centers is 5 / 11. It can be seen that a variety of lithography alignment marks can be adaptively designed according to different preset layout design rules and process requirements. By segmenting the original alignment marks, it is ensured that the figures after segmentation are evenly distributed on the center line of the original alignment marks without changing the period between the original columns. Since each column of the original alignment marks is only segmented into multiple evenly distributed figures, the figures in each column still remain on the columns of the original alignment marks. Figure 4b As shown, the original SPM X-mark alignment marks are segmented into 8×8 μm squares. The figure occupancy ratio in each column is 0.5, and the pitch is twice the original. The period between the columns of the lithography alignment marks after segmentation is twice the period between the columns of the original alignment marks. The corresponding column occupancy ratio in each cycle is reduced compared to Figure 4a the column occupancy ratio after segmentation in [reference]. The column occupancy ratio in each cycle to the left of the center is 1 / 4, and the column occupancy ratio in each cycle to the right of the center is 5 / 22. A relatively large blank is reserved between the columns. However, the figures after segmentation can be evenly distributed on the center line of the original alignment marks, that is, each column of figures after segmentation can correspond to a certain column of the original alignment marks. Figure 4c As shown, the original SPM X-mark alignment marks are segmented into 24×24 μm squares. The figure occupancy ratio in each column is 0.5, and the pitch is four times the original. The period between the columns of the lithography alignment marks after segmentation is four times the period between the columns of the original alignment marks. The column occupancy ratio in each cycle to the left of the center is 3 / 8, and the column occupancy ratio in each cycle to the right of the center is 15 / 44. The figures after segmentation can be evenly distributed on the center line of the original alignment marks, which is convenient for subsequent automatic alignment and simplifies the process flow.

[0059] Figures 4a - 4c The figures after segmentation are all complete figures. If there is a situation where incomplete figures are formed by cutting the column edges, the incomplete figures will be discarded when calculating the figure occupancy ratio in each column.

[0060] Please refer to Figure 5 , Figure 5Shown is a lithography alignment mark formed by dividing the same pattern shape, the same pattern size, the same column occupancy ratio but different pattern occupancy ratios based on the SPM X-mark alignment mark. On the premise of keeping the column-to-column period unchanged, each column of the original alignment mark is divided into circles with a diameter of 5 μm, and based on the dense pattern area in the layout, the pattern occupancy ratios in each column are designed to be 2 / 3, 1 / 2, and 1 / 3 respectively. When dividing the columns according to the described scheme, first, after arranging the largest integer number of patterns in the column direction and the sum of their adjacent blank areas, if the remaining size is greater than or equal to the size of a single pattern, one more pattern is added; if the remaining size is less than the size of a single pattern, the incomplete pattern is deleted. Figure 5 For the mark with a pattern occupancy ratio of 2 / 3, the sum of the pattern and its adjacent blank area is 7.5 μm, 9 complete periods are placed, the total size is 67.5 μm, and the remaining 4.5 μm is less than the size of a single pattern, so no pattern is placed in the remaining area; Figure 5 For the mark with a pattern occupancy ratio of 1 / 2, the sum of the pattern and its adjacent blank area is 10 μm, 7 complete periods are placed, the total size is 70 μm, and the remaining 2 μm is less than the size of a single pattern, so no pattern is placed in the remaining area; Figure 5 For the mark with a pattern occupancy ratio of 1 / 3, the sum of the pattern and its adjacent blank area is 15 μm, 4 complete periods are placed, the total size is 60 μm, and the remaining 12 μm is greater than the size of a single pattern, so one more pattern is added. Finally, the remaining 7 μm blank is an incomplete blank (the complete blank area is 10 μm) and is not shown either; Through the adaptive design method of the lithography alignment mark in this embodiment, it can be adaptively divided according to the layout design rules and process requirements, so that it can match both the process requirements and the alignment requirements of the lithography machine.

[0061] Please refer to Figure 6 , Figure 6 which is a flowchart of an alignment method provided by an embodiment of the present invention. This method is for the TSV process, and uses the lithography alignment mark formed by the adaptive design method of the lithography alignment mark to realize the full-automatic alignment process on a projection lithography machine. As Figure 5 shown, it includes:

[0062] S10. Place two groups of the lithography alignment marks described in the above embodiment of the present invention on the TSV layer layout. The two groups of lithography alignment marks are mirror-symmetrical along the Y-axis; one group is placed normally and is used for automatic alignment of the front-illuminated lithography layer (such as the Top Metal (top metal layer)); the other group is placed after being mirrored along the Y-axis with the normally placed lithography alignment mark and is used for automatic alignment of the back-illuminated lithography layer (such as the Bottom Metal (bottom metal layer)) after bonding.

[0063] S20. Prepare a wafer, perform TSV layer lithography on a projection lithography machine, and then perform etching, copper electroplating, and CMP.

[0064] Since the graphic shape, graphic size, and graphic density of the lithography alignment marks are consistent with the shapes, sizes, and graphic densities of the through-silicon vias on the TSV layer layout, in this step, the situation where the holes are prematurely sealed before being filled with copper during the copper electroplating process is avoided; the situation where the gas in the hollow holes expands to form bulges during the thermal annealing process, resulting in the scrapping of the wafer, is also avoided, and defects such as dishing (surface depression) and void (hole) are prevented from occurring at the lithography alignment marks.

[0065] S30. Perform front-side lithography of the positive lithography layer (such as Top Metal) on a projection lithography machine, automatically align with the lithography alignment marks placed normally on the TSV layer, and then perform etching.

[0066] S40. Bond and thin the wafer to expose the copper on the back side of the TSV and the back sides of the two sets of lithography alignment marks; the graphic shape and graphic size of the lithography alignment marks are consistent with the layout design rules of the TSV layer, enabling precise control of the etching depth and ensuring normal exposure of the copper on the back side of the TSV and the back sides of the two sets of lithography alignment marks.

[0067] S50. Perform back-side lithography of the back-side lithography layer (such as Bottom Metal) on a projection lithography machine, and automatically align with the lithography alignment marks that are mirror-symmetrical along the Y-axis on the TSV layer. Using the automatic alignment method instead of the manual alignment method can achieve automatic alignment on a non-contact lithography machine, improving graphic resolution, alignment accuracy, and production yield.

[0068] This embodiment can finally achieve a fully automated alignment process for the TSV process with a diameter of 1 - 25 μm, expanding the applicable range. Taking the 25-μm layout through-silicon vias as an example, it is assumed that the design requirement for the alignment mark graphic size of the layout through-silicon vias is 25 μm. The slicing module slices the original alignment mark into two rows of 25-μm graphic shapes, occupying a total of 50 μm, with a 22-μm blank space reserved between them. Maintaining an appropriate spacing can precisely achieve the fully automated alignment of the TSV process.

[0069] For the TSV process in this embodiment, the lithography alignment marks formed by the lithography alignment mark adaptive design method are used. Two sets of lithography alignment marks placed symmetrically along the Y-axis can eliminate the zero-layer alignment marks, simplify the process flow, and achieve a fully automated alignment process on a projection lithography machine, avoiding the manual alignment operation on a contact lithography machine, improving graphic resolution, alignment accuracy, and production yield. Moreover, while achieving automatic alignment, defects are prevented from occurring at the alignment marks, providing strong support for the automated production of chip-level interconnections.

[0070] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An adaptive design method for lithography alignment marks, characterized in that Including: Based on a preset layout design rule and process requirements for analysis to obtain an analysis result, the analysis result includes: graphic shape, graphic size, and graphic density; determining a lithography alignment mark according to the analysis result; the layout design rule includes the graphic shape, diameter of the silicon through-hole, and the silicon through-hole graphic density in the dense area of the layout; Determining the lithography alignment mark according to the analysis result specifically includes: splitting each column of the original alignment mark according to the analysis result, and making the period of the columns of the split lithography alignment mark the same as or an integer multiple of the period of the columns of the original alignment mark; when splitting the columns according to the analysis result, first sum the maximum integer number of graphics arranged in the column direction and their adjacent blank areas, and if the remaining size is greater than or equal to the single graphic size, add one graphic; if the remaining size is less than the single graphic size, delete the incomplete graphic; The graphic density includes the graphic ratio in each column and the column ratio in each period. The graphic ratio in each column represents the ratio of a graphic area to the sum of the graphic and its adjacent blank areas in the same column, and the adjacent blank area is selected as the blank area between two graphics; the column ratio in each period represents the ratio of a column to the sum of the column and its adjacent blank areas in one period, and the adjacent blank area is selected as the blank area between two columns; the graphic ratio in each column is 0.2 - 1, and there is at least one complete graphic in each column; the column ratio in each period is 0.2 - 0.8, and the gap between columns is reserved.

2. The lithography alignment mark adaptive design method according to claim 1, wherein The graphic shape is one of a rectangle, a square, a rounded rectangle, and a circle.

3. The lithography alignment mark adaptive design method according to claim 1, characterized in that The graphic size is 1 - 72 μm.

4. A lithography alignment mark adaptive design device, characterized in that Including: An analysis module for performing analysis based on a preset layout design rule and process requirements to obtain an analysis result, the analysis result includes: graphic shape, graphic size, and graphic density; the layout design rule includes the graphic shape, diameter of the silicon through-hole, and the silicon through-hole graphic density in the dense area of the layout; A lithography alignment mark determination module for determining a lithography alignment mark according to the analysis result; the lithography alignment mark determination module includes a splitting module for splitting each column of the original alignment mark according to the analysis result, and making the period of the columns of the split lithography alignment mark the same as or an integer multiple of the period of the columns of the original alignment mark; When splitting the columns according to the analysis result, first sum the maximum integer number of graphics arranged in the column direction and their adjacent blank areas, and if the remaining size is greater than or equal to the single graphic size, add one graphic; if the remaining size is less than the single graphic size, delete the incomplete graphic; The graphic density includes the proportion of graphics in each column and the proportion of columns in each period. The proportion of graphics in each column represents the ratio of a graphic area to the sum of the graphic and its adjacent blank areas in the same column. The adjacent blank areas selected are the blank areas between two graphics. The proportion of columns in each period represents the ratio of a column to the sum of the column and its adjacent blank areas in one period. The adjacent blank areas selected are the blank areas between two columns. The proportion of graphics in each column is 0.2 - 1, and there is at least one complete graphic in each column. The proportion of columns in each period is 0.2 - 0.8, and the gaps between columns are reserved.

5. A lithography alignment mark, characterized in that, Formed by using the lithography alignment mark adaptive design method according to any one of claims 1 - 3.

6. An alignment method, characterized in that, Including: Placing two sets of the lithography alignment marks described in claim 5 on the TSV layer layout. The two sets of lithography alignment marks are mirror-symmetrical along the Y-axis. One set is placed normally for automatic alignment of the front-illumination photolithography layer. The other set is placed after being mirrored along the Y-axis with respect to the normally placed lithography alignment marks for automatic alignment of the back-illumination photolithography layer after bonding. Preparing a wafer, and performing TSV layer photolithography, etching, copper electroplating, and CMP. Performing front-illumination photolithography layer photolithography and automatically aligning with one set of the lithography alignment marks on the TSV layer. Bonding and thinning to expose the copper on the back of the TSV and the backs of the two sets of the lithography alignment marks. Performing back-illumination photolithography layer photolithography and automatically aligning with the other set of the lithography alignment marks on the TSV layer.

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