Photolithography alignment matching method and computer readable storage medium

Abstract

This application relates to a photolithography alignment matching method and a computer-readable storage medium. The method includes: performing one photolithography step using a first photolithography machine to transfer a target alignment mark to a dicing channel of a target wafer, obtaining a first mark located at a first position; performing one photolithography step using a second photolithography machine to transfer the target alignment mark to a dicing channel of the target wafer, obtaining a second mark located at a second position; the first mark and the second mark are designed to be at the same position on the target wafer; obtaining the positional deviation between the second mark and the first mark; performing alignment compensation on the exposure menu of the second photolithography machine according to the positional deviation; and the second photolithography machine completing subsequent exposure processes on the target wafer according to the alignment-compensated exposure menu. This invention has a simple operation process, saving significant manpower and machine time. Furthermore, it eliminates the risk of wafer fragmentation and contamination. No new equipment needs to be added; existing equipment on the production line can be used.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a photolithography alignment matching method, and also to a computer-readable storage medium. Background Technology

[0002] In the development of some chip products, wafer foundries (Fabs) may receive orders from customers where the front-end processes are done by Company A, and the back-end processes by Company B. While some production data between the two companies can be obtained from the customer, highly confidential data, such as sensitive information like lithography machine parameter settings, cannot be obtained from the customer. Therefore, during the process development of some products, Company B needs to verify some parameter settings from Company A through experiments. For example, Company B may encounter situations where wafers with alignment marks from Company A are rejected, requiring modification of the lithography alignment parameters to achieve alignment matching.

[0003] Traditional methods require repeatedly trying different lithography alignment parameters to find the gap (difference) between lithography machines in two fabs and achieve alignment matching. This approach is very time-consuming and labor-intensive, which not only prolongs the development cycle but also increases development costs. Summary of the Invention

[0004] Therefore, it is necessary to provide a photolithographic alignment matching method.

[0005] A photolithography alignment matching method includes: acquiring a target wafer, wherein a first mark is formed on the target wafer at a first position of a dicing channel by a first photolithography machine through a single photolithography step to transfer a target alignment mark; performing a single photolithography step using a second photolithography machine to transfer the target alignment mark to the dicing channel of the target wafer, resulting in a second mark at a second position; the first mark and the second mark have the same designed position on the target wafer; acquiring the positional deviation between the second mark and the first mark; performing alignment compensation on the exposure menu of the second photolithography machine according to the positional deviation; and the second photolithography machine completing subsequent exposure processes on the target wafer according to the alignment-compensated exposure menu.

[0006] In the above-mentioned photolithography alignment matching method, the first mark and the second mark are formed through a single photolithography transfer. Therefore, the positional deviation between the second mark and the first mark is caused by the alignment deviation during pre-alignment. By performing alignment compensation on the exposure menu of the second photolithography machine based on this positional deviation, the photolithography alignment matching can be completed.

[0007] In one embodiment, when the first lithography machine performs pattern transfer of the target alignment mark through a single lithography step, the target wafer is in a pre-aligned state by the first lithography machine; when the second lithography machine performs a single lithography step, the target wafer is in a pre-aligned state by the second lithography machine.

[0008] In one embodiment, the pre-alignment of the first lithography machine and the pre-alignment of the second lithography machine are performed based on the position of the notch on the target wafer.

[0009] In one embodiment, the target alignment mark includes a mark pattern for forming on each of the four sides of the edge of the exposure area, wherein the X-axis coordinates of two mark patterns on a set of opposite sides extending along the X-axis of the exposure area are equal, and the Y-axis coordinates of two mark patterns on a set of opposite sides extending along the Y-axis are equal.

[0010] In one embodiment, each of the marked graphics includes two connected line segments that are perpendicular to each other.

[0011] In one embodiment, the first line segment of the two line segments is perpendicular to the edge of the exposure area, and the second line segment is located at the edge of the exposure area. The width ratio of the first line segment to the second line segment is 2:1.

[0012] In one embodiment, each of the marked graphics is a semicircle, the second line segment is the diameter of the semicircle, and the first line segment is the radius of the semicircle.

[0013] In one embodiment, the step of obtaining the positional deviation between the second mark and the first mark includes obtaining the positional deviation between the second mark and the first mark in multiple exposure areas and calculating the average positional deviation; the step of aligning the exposure menu of the second lithography machine according to the positional deviation is to perform alignment compensation based on the average positional deviation.

[0014] In one embodiment, the step of aligning the exposure menu of the second lithography machine according to the position deviation further includes: importing the position deviation into an overlay error analysis system, obtaining an overlay error compensation value using an overlay error algorithm, and compensating the exposure menu using the overlay error compensation value.

[0015] In one embodiment, some or all of the process parameters of the first lithography machine when transferring the target alignment mark in a single lithography process are unknown.

[0016] In one embodiment, the first lithography machine and the second lithography machine are lithography machines equipped in different wafer fabs.

[0017] It is also necessary to provide a readable storage medium on which a computer program is stored, which, when executed by a processor, implements the steps of the photolithography alignment matching method described in any of the above embodiments.

[0018] It is also necessary to provide a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the photolithography alignment matching method described in any of the above embodiments.

[0019] It is also necessary to provide a computer program product, including a computer program that, when executed by a processor, implements the steps of the photolithography alignment matching method described in any of the foregoing embodiments. Attached Figure Description

[0020] To better describe and illustrate embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the currently described embodiments and / or examples, or the best mode of these inventions as currently understood.

[0021] Figure 1 This is a flowchart of a photolithographic alignment matching method in one embodiment of this application.

[0022] Figure 2 This is a schematic diagram of the target alignment mark on the photomask in one embodiment of this application.

[0023] Figure 3 This is a schematic diagram of the first mark A and the second mark B in four adjacent shots after exposure by the second lithography machine.

[0024] Figure 4 This is a pattern of a marker graphic in one embodiment of this application.

[0025] Figure 5 This is a schematic diagram of position measurement using 27 shot markers selected in one embodiment of this application. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0029] 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.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0031] Embodiments of the invention are described herein with reference to cross-sectional views that serve as schematic diagrams of ideal embodiments (and intermediate structures). Thus, variations in the shape shown can be anticipated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the invention should not be limited to the specific shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing processes. For example, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, the buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to show the actual shapes of the regions of the device and are not intended to limit the scope of the invention.

[0032] As described in the background section, there is currently no particularly effective method to find the gap (gap) between lithography machines in two fabs. The method described in the background section, which involves continuously adjusting pre-alignment parameters and then testing, may require multiple rejections before achieving alignment. This method consumes a significant amount of manpower and machine time, leading to extended process development cycles, and there is a risk of wafer fragmentation during the experiment, which can contaminate the machine.

[0033] This application proposes an innovative photolithography alignment matching method. Using a single photolithography process, two photolithography machines are used to create alignment marks. By measuring these alignment marks, the gaps (GAPs) of alignment systems in different fabs can be quickly obtained. This achieves seamless integration between different wafer fabs and different production systems. Figure 1 This is a flowchart of a photolithographic alignment matching method in one embodiment of this application, including the following steps:

[0034] S110, acquire the target wafer.

[0035] At the first position of the dicing channel on the target wafer, a first mark is formed by the first lithography machine transferring the target alignment mark through a single lithography step. See also Figure 2The photomask 100 used in this photolithography process has target alignment marks formed on it. A single photolithography step is the first photolithography step performed after pre-alignment (pre-alignment) by the photolithography machine. Following photolithography, etching is performed to transfer the target alignment marks to the dicing channels (wiring channels) of the target wafer. The pattern obtained by transferring the target alignment marks to the dicing channels of the target wafer is denoted as the first mark A, and its position is denoted as the first position, with coordinates (a, b). In one embodiment of this application, other test patterns are provided at the four corners of the photomask 100. Figure 2 These test graphics are omitted from the text.

[0036] S120, use the second lithography machine to perform one lithography step to obtain the second mark located at the second position.

[0037] A second lithography machine is used for lithography and etching, transferring the target alignment mark to the dicing channel of the target wafer, resulting in the second mark B. If the alignment parameters of the first and second lithography machines are identical (GAP), the position of the second mark B should be the same as that of the first mark A. However, in actual production, due to differences in the alignment parameters of the first and second lithography machines, the second mark B is located at a second position different from the first position. See [link to relevant documentation]. Figure 3 The coordinates of the second position are (m, n). Figure 3 To make it easier to distinguish between the first mark A and the second mark B, the second mark B was made semi-transparent.

[0038] S130, obtain the positional deviation between the second mark and the first mark.

[0039] In one embodiment of this application, the positional deviation is calculated by determining the coordinate difference between the second marker B and the first marker A. Specifically, the positional deviation in the X-axis direction is am, and the positional deviation in the Y-axis direction is bn.

[0040] S140 performs alignment compensation on the exposure menu of the second lithography machine based on the positional deviation.

[0041] The positional deviation obtained in step S130 is the gap between the second lithography machine and the first lithography machine. By compensating for this gap, alignment matching can be achieved. Based on the aforementioned first and second positions, the pre-alignment positional deviation compensation value is (am, bn), which is the offset of a point within one shot. In one embodiment of this application, to obtain a more accurate compensation value, the positional deviations of the four marker patterns within one shot are measured respectively, and imported into the overlay error (OVL) measurement value calculation macro to obtain a more accurate positional deviation compensation value.

[0042] S150, the second lithography machine completes the subsequent exposure process on the target wafer according to the exposure menu after alignment compensation.

[0043] In the above-described photolithography alignment method, the first mark A and the second mark B are formed through a single photolithography transfer. Therefore, the positional deviation between the second mark B and the first mark A is caused by the alignment deviation during pre-alignment. By compensating for this positional deviation in the exposure menu of the second photolithography machine, photolithography alignment can be completed. This method is simple to operate and can save significant manpower and machine time. Furthermore, there is no risk of wafer fragmentation or contamination. No new equipment needs to be added; existing equipment on the production line can be used.

[0044] In one embodiment of this application, when the first lithography machine performs pattern transfer of the target alignment mark through one lithography step, the target wafer is in a pre-aligned state by the first lithography machine; when step S120 performs one lithography step, the target wafer is in a pre-aligned state by the second lithography machine.

[0045] In one embodiment of this application, the pre-alignment of the first lithography machine and the pre-alignment of the second lithography machine are performed based on the position of the notch of the target wafer, that is, the pre-alignment is performed with the notch as the reference point.

[0046] See Figure 2 The target alignment markers include one marker pattern on each of the four sides of the exposure area (shot), namely marker pattern 11, marker pattern 12, marker pattern 13, and marker pattern 14. The X-axis coordinates of two marker patterns (marker pattern 11 and marker pattern 13) on a pair of opposite sides extending along the X-axis of the exposure area are equal, and the Y-axis coordinates of two marker patterns (marker pattern 12 and marker pattern 14) on a pair of opposite sides extending along the Y-axis are equal. This ensures that two adjacent shots will have two marker patterns combined on their overlapping sides to form a complete pattern.

[0047] Figure 4 This is a pattern of a marker graphic in one embodiment of this application. Each marker graphic includes two connected line segments (i.e., a first line segment 112 and a second line segment 114), and these two line segments are perpendicular to each other.

[0048] In one embodiment of this application, the first line segment 112 is perpendicular to the edge of the shot, and the second line segment 114 is located on the edge of the shot. The first line segment 112 is twice as thick as the second line segment 114, that is, the width ratio of the first line segment 112 to the second line segment 114 is 2:1. In one embodiment of this application, each marker graphic is a semicircle, the second line segment 114 is the diameter of the semicircle, and the first line segment 112 is the radius of the semicircle. See also Figure 3Since two marker graphics will combine to form a complete graphic at the edge of the shot, the two second line segments 114 will stick together to form a line segment twice as thick. Therefore, the first line segment 112 can be set to be twice as thick as the second line segment 114. This setting can also prevent different specifications of the cutting track design and make it easy to distinguish them.

[0049] In one embodiment of this application, the diameter of the semi-circular marking pattern is 30 micrometers, the first line segment 112 is 1 micrometer thick, and the second line segment 114 is 0.5 micrometer thick.

[0050] In one embodiment of this application, step S130 includes acquiring the positional deviations of the second mark B and the first mark A in multiple exposure areas, and calculating the average positional deviation. The average positional deviations along the X-axis and Y-axis can be calculated using the following formula:

[0051]

[0052]

[0053] Where n is the number of shots selected for calculating the average positional deviation, X 11 X 12 X 13 X 14 The X-axis position deviation of the four marked graphics in a shot, Y 11 Y 12 Y 13 Y 14 The Y-axis position deviation of the four marked graphics in a shot. Accordingly, step S140 is to perform alignment compensation based on the average position deviation.

[0054] In one embodiment of this application, a wafer is selected as such Figure 5 27 shots with medium-dark fill (excluding) Figure 5 The average positional deviation is calculated using the shot in the lower left corner of the middle. Specifically, an overlay error (OVL) instrument can be used to measure the coordinates of the first and second marks within each shot, calculate the positional deviation, and take the average value as the average positional deviation. Step S140 then performs alignment compensation based on the average positional deviation. Figure 5 The numbers in the diagram are used to number each shot. Since the achievement of the purpose of this invention does not depend on these numbers, therefore... Figure 5 The numbers in the text can be ignored.

[0055] In one embodiment of this application, step S140 further includes:

[0056] S142, the position deviation is imported into the overlay error (OVL) analysis system, and the overlay error compensation value is obtained by using the overlay error (OVL) algorithm.

[0057] By importing the measured value of the position deviation into the OVL data calculation algorithm macro, the ten compensation values ​​of OVL can be obtained.

[0058] S144 compensates for the exposure menu using overlay error compensation values.

[0059] By further compensating for overlay error values ​​within the exposure menu, seamless integration between different fabrics can be achieved, thereby enhancing the competitiveness of the fabric.

[0060] As mentioned above, the lithography alignment matching method of this application is applicable to lithography alignment matching across fabs, i.e., when the first lithography machine and the second lithography machine are equipped in different wafer fabs. In this case, the wafer fab of the second lithography machine cannot know the lithography alignment parameters of the first lithography machine. That is, some or all of the process parameters (i.e., the machine parameters of the lithography machine, including lithography alignment parameters, process menu parameters, etc.) when the first lithography machine transfers the target alignment mark in one lithography operation are unknown. It is understood that the lithography alignment matching method of this application is also applicable to lithography alignment matching between different production systems within the same fab, i.e., it is also applicable to the case where the first lithography machine and the second lithography machine are all owned by the same wafer fab.

[0061] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0062] This application provides a readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the photolithography alignment matching method described in any of the above embodiments.

[0063] This application provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the photolithography alignment matching method described in any of the above embodiments.

[0064] This application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the photolithography alignment matching method described in any of the foregoing embodiments.

[0065] It should be understood that although the steps in the flowchart of this application are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart of this application may include multiple steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but may be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0066] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" 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 the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above 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.

[0068] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A photolithographic alignment method, comprising: A target wafer is obtained, wherein a first mark is formed at a first position of the dicing channel by a first lithography machine through a single lithography process to transfer the target alignment mark; A second lithography machine is used to perform a single lithography step, transferring the target alignment mark to the dicing channel of the target wafer to obtain a second mark located at the second position; the first mark and the second mark are designed to be in the same position on the target wafer; Obtain the positional deviation between the second mark and the first mark; The exposure menu of the second lithography machine is aligned and compensated according to the positional deviation. The second lithography machine completes the subsequent exposure process on the target wafer according to the exposure menu after alignment compensation.

2. The lithography alignment matching method according to claim 1, wherein When the first lithography machine transfers the target alignment mark through a single lithography process, the target wafer is in a pre-aligned state by the first lithography machine. When performing a photolithography process using the second photolithography machine, the target wafer is in a pre-aligned state by the second photolithography machine.

3. The lithography alignment matching method according to claim 1, wherein The first lithography machine pre-alignment and the second lithography machine pre-alignment are performed based on the position of the notch on the target wafer.

4. The lithography alignment matching method according to claim 1, wherein The target alignment mark includes a mark pattern formed on each of the four sides of the edge of the exposure area. The X-axis coordinates of two mark patterns on a pair of opposite sides extending along the X-axis of the exposure area are equal, and the Y-axis coordinates of two mark patterns on a pair of opposite sides extending along the Y-axis are equal.

5. The lithography alignment matching method according to claim 4, wherein Each of the marked graphics comprises two connected line segments that are perpendicular to each other.

6. The lithography alignment matching method according to claim 5, wherein The first line segment is perpendicular to the edge of the exposure area, and the second line segment is located at the edge of the exposure area. The width ratio of the first line segment to the second line segment is 2:

1.

7. The lithography alignment matching method according to claim 6, wherein Each of the marked graphics is a semicircle, the second line segment is the diameter of the semicircle, and the first line segment is the radius of the semicircle.

8. The lithography alignment matching method of claim 1, wherein, The step of obtaining the positional deviation between the second mark and the first mark includes obtaining the positional deviation between the second mark and the first mark in multiple exposure areas and calculating the average positional deviation; The step of aligning the exposure menu of the second lithography machine according to the position deviation is to perform alignment compensation based on the average position deviation.

9. The lithography alignment matching method according to claim 1, wherein, Some or all of the process parameters of the first lithography machine when transferring the target alignment mark in a single lithography process are unknown.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1-9.

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