Sampling method and sampling device for measuring overlay error
By acquiring process information of the lithography pattern to divide the batches to be sampled and performing sampling tests on overlay errors, the problem of inadequate monitoring of some composite layers during the lithography process was solved, and the overlay accuracy and process monitoring capabilities were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGXIN MEMORY TECH INC
- Filing Date
- 2022-06-28
- Publication Date
- 2026-07-31
AI Technical Summary
In existing technologies, the overlay error monitoring of some composite layers during the photolithography process is inadequate, resulting in poor process monitoring capabilities.
By acquiring the process information of the target front layer pattern, multiple sampling batches are divided according to the first process information and the second process information, and the overlay error of each batch is sampled and tested to ensure that different combined layers are sampled and inspected.
It effectively alleviates the problem of inadequate monitoring of overlay errors in some composite layers during photolithography, and improves the process monitoring capability and the controllability of overlay accuracy.
Smart Images
Figure CN115047726B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and more specifically, to a sampling method, sampling device, electronic device, computer-readable storage medium, and photolithography system for measuring overlay error. Background Technology
[0002] The overlay error between the current lithography layer and the previous lithography layer is used to characterize the relative displacement of two or more related layers. To ensure that the overlay error between lithography layers is controllable and to provide a more accurate basis for parameter adjustment in subsequent processes, existing technologies use online sampling methods to determine the overlay error of lithography layers. Current online sampling rules are based on the LOT ID (Wafer Batch ID) of the lithography layer. For example, lithography layer batches with the last digit of the LOT ID being 1 or 2 use a 20% sampling ratio, while lithography layer batches with the last digit of the LOT ID being 3, 4, or 5 use a 30% sampling ratio.
[0003] The above setup method may result in some associated layer combinations being missed during sampling, leading to inadequate monitoring of overlay errors in some associated layers.
[0004] The information disclosed above in the background section is only intended to enhance the understanding of the background art of the art described herein. Therefore, the background art may contain certain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention
[0005] The main objective of this application is to provide a sampling method, sampling device, electronic device, computer-readable storage medium, and photolithography system for measuring overlay error, so as to solve the problem of inadequate monitoring of overlay error of some composite layers in the photolithography process in the prior art.
[0006] According to one aspect of the embodiments of this application, a sampling method for measuring overlay error is provided, comprising: acquiring first process information, wherein the first process information is process information of a target front-layer pattern, and the target front-layer pattern is a front-layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; determining a plurality of sampling batches based at least on the first process information, wherein the first process information of each target front-layer pattern in the same sampling batch is the same; and sampling and measuring the overlay error of each sampling batch.
[0007] Optionally, obtaining first process information includes: determining the preceding layer factors that affect the overlay accuracy; determining the preceding layer lithography pattern related to the preceding layer factors as the target preceding layer pattern; obtaining the process information of the target preceding layer pattern to obtain the first process information.
[0008] Optionally, before determining multiple batches to be sampled based at least on the first process information, the method further includes: obtaining second process information, wherein the second process information is the process information of the current layer lithography pattern.
[0009] Optionally, at least based on the first process information, multiple batches to be sampled are determined, including: determining multiple batches to be sampled based on the first process information and the second process information, wherein the second process information of the current layer lithography pattern is the same in the same batch to be sampled.
[0010] Optionally, determining multiple batches to be sampled based on the first process information and the second process information includes: dividing the final patterns corresponding to different first process information into different first predetermined batches, wherein the final pattern is composed of the overlaid previous layer lithography pattern and the current layer lithography pattern; dividing the final patterns corresponding to different second process information in the first predetermined batches into different second predetermined batches to obtain multiple batches to be sampled.
[0011] Optionally, the first process information includes first processing time period information. Dividing the final graphics corresponding to different first process information into different first predetermined batches includes: dividing the final graphics corresponding to different first process information into different third predetermined batches; and, based on the first processing time period information of each target front layer graphic, taking the final graphics corresponding to the target front layer graphic that are located in the same first processing cycle in each third predetermined batch as a first predetermined batch, thereby obtaining multiple first predetermined batches.
[0012] Optionally, the second process information includes second processing time period information. Dividing the final patterns corresponding to different second process information in the first predetermined batch into different second predetermined batches includes: dividing the final patterns corresponding to different second process information in the first predetermined batch into different fourth predetermined batches; and, based on the second processing time period information of the current layer lithography pattern, taking the final patterns corresponding to the current layer lithography pattern within the same second processing cycle in each of the fourth predetermined batches as a second predetermined batch, thereby obtaining multiple second predetermined batches.
[0013] Optionally, the overprinting error of each of the batches to be sampled is sampled and tested separately, including: obtaining the sampling ratio corresponding to different batches to be sampled; and sampling and testing the overprinting error of the corresponding batches to be sampled according to the sampling ratio.
[0014] Optionally, the first process information includes the processing machine information of the target front-end pattern and the comprehensive process capability index corresponding to the processing machine, and obtaining the sampling ratio corresponding to different batches to be sampled includes: determining the corresponding sampling ratio according to the comprehensive process capability index corresponding to each batch to be sampled, wherein the comprehensive process capability index is negatively correlated with the sampling ratio.
[0015] Optionally, after sampling and testing the overprinting error of each of the batches to be sampled, the method further includes: determining corrected process parameters for reducing the overprinting error based on the overprinting error; and sending the process parameters to the processing machine.
[0016] Optionally, the first process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the target front-layer pattern.
[0017] Optionally, the second process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the current layer photolithography pattern.
[0018] According to another aspect of the embodiments of this application, a sampling device for measuring overlay error is also provided, including a first acquisition unit, a first determination unit, and a sampling unit. The first acquisition unit is used to acquire first process information, which is process information of a target front-layer pattern, wherein the target front-layer pattern is a front-layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern. The first determination unit is used to determine multiple batches to be sampled, at least based on the first process information, wherein the first process information of each target front-layer pattern in the same batch to be sampled is the same. The sampling unit is used to sample the overlay error of each batch to be sampled.
[0019] According to another aspect of the embodiments of this application, an electronic device is also provided, the electronic device including a memory, a processor, and a computer program stored in the memory, wherein the computer program, when executed by the processor, implements the steps of any of the methods described in this application.
[0020] According to another aspect of the embodiments of this application, a computer-readable storage medium is also provided, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the steps of any of the methods described in this application.
[0021] According to another aspect of the embodiments of this application, a lithography system is also provided, the lithography system including a lithography machine and a control device for the lithography machine, the control device including a memory, a processor and a computer program stored in the memory, the computer program being executed by the processor to implement the steps of any of the methods described in this application.
[0022] The sampling method for measuring overlay error using the technical solution of this application involves, firstly, obtaining the first process information of the target front-layer pattern, where the target front-layer pattern is the front-layer lithography pattern that affects the overlay accuracy of the current lithography pattern; then, determining multiple sampling batches based at least on the first process information, where the first process information of the target front-layer pattern is the same in each sampling batch; and finally, sampling and measuring the overlay error of each sampling batch. The method of this application, based on different process information of the front-layer lithography pattern related to the overlay accuracy of the current lithography pattern, divides the combination of the front-layer lithography pattern and the current lithography pattern into multiple sampling batches, ensuring that the process information of each front-layer lithography pattern in different sampling batches is different. This guarantees that most combinations of different front-layer lithography patterns and the current lithography pattern will be sampled, avoiding the problem of inadequate monitoring of some combined layers, ensuring good process monitoring capability, and relatively controllable overlay accuracy, effectively alleviating the problem of inadequate monitoring of overlay errors of some combined layers in the lithography process of existing technologies. Attached Figure Description
[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:
[0024] Figure 1 A schematic flowchart of a sampling method for measuring overlay error according to an embodiment of this application is shown;
[0025] Figure 2 A schematic diagram of a sampling apparatus for measuring overlay error according to an embodiment of this application is shown. Detailed Implementation
[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.
[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.
[0028] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0029] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.
[0030] As mentioned in the background section, the overlay error monitoring of some composite layers in the photolithography process of the prior art is inadequate. In order to solve the above problems, in a typical embodiment of this application, a sampling method, sampling device, electronic device, computer-readable storage medium and photolithography system for measuring overlay error are provided.
[0031] According to an embodiment of this application, a sampling method for measuring overlay error is provided.
[0032] Figure 1 This is a flowchart of a sampling method for measuring overlay error according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:
[0033] Step S101: Obtain first process information, wherein the first process information is the process information of the target front layer pattern, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern.
[0034] Step S102: Based on the first process information mentioned above, determine multiple batches to be sampled, wherein the first process information of each of the target front layer patterns in the same batch to be sampled is the same.
[0035] Step S103: The overlay error of each of the above-mentioned batches to be sampled is sampled and tested.
[0036] In the above-described sampling method for measuring overlay error, firstly, the first process information of the target front-layer pattern is obtained, where the target front-layer pattern is the front-layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; then, based at least on the first process information, multiple sampling batches are determined, where the first process information of the target front-layer pattern in each sampling batch is the same; finally, the overlay error of each of the above sampling batches is sampled. The method of this application, based on different process information of the front-layer lithography pattern related to the overlay accuracy of the current layer lithography pattern, divides the combination of the front-layer lithography pattern and the current layer lithography pattern into multiple sampling batches, ensuring that the process information of each front-layer lithography pattern in different sampling batches is different. This guarantees that most combinations of different front-layer lithography patterns and the current layer lithography pattern will be sampled, avoiding the problem of inadequate monitoring of some combination layers, ensuring good process monitoring capability, and relatively controllable overlay accuracy, effectively alleviating the problem of inadequate monitoring of overlay errors of some combination layers in the lithography process of existing technologies.
[0037] Specifically, the aforementioned target front-layer pattern can be a single front-layer lithography pattern that affects the current lithography pattern, or it can include multiple front-layer lithography patterns that affect the current lithography pattern. When the aforementioned target front-layer pattern includes multiple front-layer lithography patterns that affect the current lithography pattern, each front-layer lithography pattern is numbered and analyzed.
[0038] To ensure a relatively simple and accurate acquisition of the first process information, according to a specific embodiment of this application, obtaining the first process information includes: determining the preceding layer factors affecting the overlay accuracy; determining the preceding layer lithography pattern related to the preceding layer factors as the target preceding layer pattern; and obtaining the process information of the target preceding layer pattern to obtain the first process information. By identifying the preceding layer factors affecting the overlay accuracy, the target preceding layer pattern is found, ensuring that the target preceding layer pattern can be found relatively quickly and that the found target preceding layer pattern is relatively accurate, as they are all preceding layer lithography patterns related to the overlay accuracy of the current layer lithography pattern. This ensures that the obtained first process information is relatively accurate, and further ensures that the sampling batch obtained based on the first process information can basically include the combination of the preceding layer lithography pattern and the current layer lithography pattern. This further alleviates the problem of inadequate monitoring of overlay errors in some combined layers during existing lithography processes, resulting in poor process monitoring capabilities.
[0039] According to another specific embodiment of this application, before determining multiple batches to be sampled based at least on the first process information, the method further includes: obtaining second process information, wherein the second process information is the process information of the current layer lithography pattern. Due to machine instability and differences in different process equipment, the overlay errors between the various current layer lithography patterns obtained are also different. To further ensure that different combinations of previous layer lithography patterns and current layer lithography patterns are basically sampled, and to minimize the possibility of missed sampling of combinations of previous layer lithography patterns and current layer lithography patterns within a certain period, this application also obtains the second process information of the current layer lithography pattern. This facilitates subsequent batching of products combining previous layer lithography patterns and current layer lithography patterns to be sampled, taking into account both the first and second process information.
[0040] In another specific embodiment of this application, at least based on the aforementioned first process information, multiple sampling batches are determined, including: determining multiple sampling batches based on the aforementioned first process information and the aforementioned second process information, wherein within the same sampling batch, the aforementioned second process information of the current layer lithography pattern is the same. By dividing different first process information and different combinations of first process information into different sampling batches, the effect of essentially sampling and testing all combinations of previous layer lithography patterns and current layer lithography patterns during the lithography process is further achieved.
[0041] In practical applications, those skilled in the art can select any suitable method to determine multiple batches to be sampled based on the first process information and the second process information. In a specific embodiment of this application, determining multiple batches to be sampled based on the first process information and the second process information includes: dividing the final patterns corresponding to different first process information into different first predetermined batches, wherein the final pattern is composed of the overlaid previous layer lithography pattern and the current layer lithography pattern; dividing the final patterns corresponding to different second process information in the first predetermined batches into different second predetermined batches, thereby obtaining multiple batches to be sampled.
[0042] Of course, the specific process for determining multiple batches to be sampled based on the first process information and the second process information is not limited to the process described above. Those skilled in the art can also use other methods to determine multiple batches to be sampled. For example, determining multiple batches to be sampled based on the first process information and the second process information includes: dividing the final patterns corresponding to different second process information into different fifth predetermined batches, wherein the final pattern is composed of the overlaid previous layer lithography pattern and the current layer lithography pattern; dividing the final patterns corresponding to different first process information in the fifth predetermined batches into different sixth predetermined batches, thereby obtaining multiple batches to be sampled.
[0043] To further alleviate the problem of inadequate monitoring of overlay errors in some composite layers during photolithography and to further ensure that the overlay accuracy of the photolithography process is more controllable, according to another specific embodiment of this application, the first process information includes first processing time information. Dividing the final patterns corresponding to different first process information into different first predetermined batches includes: dividing the final patterns corresponding to different first process information into different third predetermined batches; and, based on the first processing time information of each target front layer pattern, taking the final patterns corresponding to the target front layer patterns within the same first processing cycle in each of the third predetermined batches as one of the first predetermined batches, thereby obtaining multiple first predetermined batches.
[0044] It should be noted that the aforementioned first processing time period information refers to the start and end times of processing the target front-end graphic. That is, the first processing time period information includes the start and end times of processing the target front-end graphic, and the first processing cycle is a preset time period. The aforementioned target front-end graphics located within the same first processing cycle refer to those whose processing start and end times all fall within the same first processing cycle. For example, when the first processing cycle is from 12:00 to 15:00, multiple target front-end graphics with first processing time periods of 12:05 to 12:55, 12:30 to 13:20, and 13:00 to 15:00 are considered as the aforementioned first predetermined batch.
[0045] Specifically, the aforementioned second process information includes second processing time period information. The final patterns corresponding to different second process information within the first predetermined batch are divided into different second predetermined batches. This includes: dividing the final patterns corresponding to different second process information within the first predetermined batch into different fourth predetermined batches; and, based on the second processing time period information of the current layer lithography pattern, grouping the final patterns corresponding to the current layer lithography pattern within the same second processing cycle in each of the fourth predetermined batches into one second predetermined batch, thus obtaining multiple second predetermined batches. This further reduces the possibility of skipping some combined products of the previous and current layer lithography patterns, further ensuring that the overlay accuracy of the lithography process is more controllable.
[0046] It should be noted that the aforementioned second processing time period information refers to the start and end times of processing the current layer lithography pattern. That is, the second processing time period information includes the start and end times of processing the current layer lithography pattern, and the second processing cycle is a preset time period. The aforementioned current layer lithography pattern located within the same second processing cycle refers to the current layer lithography pattern whose processing start and end times all fall within the same aforementioned second processing cycle. For example, when the second processing cycle is from 4 PM to 10 PM, multiple current layer patterns with first processing time periods of 5:20 PM to 7:20 PM, 6:00 PM to 8:00 PM, and 9:00 PM to 10:00 PM are considered as the aforementioned second predetermined batch.
[0047] The first processing cycle and the second processing cycle mentioned above can be determined based on the duration of changes in processing parameters that affect the overlay error of the target front layer pattern or the current layer lithography pattern, such as the stability of the machine tool and the adjustment interval of the machine tool parameters. Those skilled in the art can determine the first processing cycle and the second processing cycle based on the actual influencing parameters. Moreover, the first processing cycle and the second processing cycle mentioned above are not fixed, but can be flexibly adjusted according to the actual situation.
[0048] In another specific embodiment, the overlay error of each of the aforementioned batches to be sampled is sampled and tested, including: obtaining the sampling ratio corresponding to different batches to be sampled; and sampling and testing the overlay error of the corresponding batches to be sampled according to the sampling ratio. Sampling and testing different batches to be sampled according to the sampling ratio further achieves effective monitoring of overlay errors during the photolithography process, further ensuring that process anomalies can be detected and addressed in a timely manner. Those skilled in the art can set the above sampling ratio using a RUN-to-RUN system.
[0049] Furthermore, the aforementioned first process information includes the processing machine information for the target front-end pattern and the corresponding Complex Process Capability Index (Cpk) for the processing machine. This involves obtaining the sampling ratios for different batches to be sampled, including: determining the corresponding sampling ratio based on the Complex Process Capability Index for each batch to be sampled. The Complex Process Capability Index is negatively correlated with the sampling ratio. Cpk is a quantitative reflection of process level and represents the level of process capability. Determining the sampling ratio of the final pattern produced by different machines based on their Cpk further ensures that the determined sampling ratio is reasonable, thereby further ensuring good process monitoring capabilities for the lithography process, further reducing the generation of defective products, and ensuring good overall quality of the final pattern obtained.
[0050] Specifically, in one implementation, the sampling ratio for the Lot level, corresponding to the Cpk of the processing machine, can be planned as follows:
[0051] When Cpk < 0.67, the sampling ratio can be 20%;
[0052] When Cpk < 1, the sampling ratio can be 10%;
[0053] When Cpk≥1, the sampling ratio can be 5%;
[0054] When Cpk≥1.33, the sampling ratio can be 2%.
[0055] In order to further ensure that the overlay error of the product obtained by photolithography meets the design requirements and to further achieve effective control over the overlay accuracy of the product obtained by photolithography, in another specific embodiment of this application, after sampling and testing the overlay error of each of the above-mentioned batches to be sampled, the method further includes: determining the corrected process parameters for reducing the overlay error based on the overlay error; and sending the process parameters to the processing machine.
[0056] In practical applications, those skilled in the art can, based on experience, list the process information of the previous layer lithography pattern that affects the overlay accuracy, and then verify these process information one by one to determine the aforementioned first process information. Alternatively, the first process information of the selected previous layer lithography pattern can be determined by aligning the current layer lithography pattern with the previous layer lithography pattern, such as side circuits, array areas, BEOL (Back End of Line) metal routing, and contact lines. Furthermore, the aforementioned second process information can be determined by analyzing the overlay data of the current layer lithography pattern to predict faults and input sources, such as the machine for previous layer lithography pattern 1 and the photomask for previous layer lithography pattern 2. The process for determining the second process information is the same as the process for determining the first process information, and will not be elaborated here. Of course, the specific methods for determining the aforementioned first and second process information are not limited to the methods described above. Those skilled in the art can flexibly choose appropriate methods according to the actual situation, or flexibly adjust the aforementioned methods. In one specific embodiment, the first process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the target front-layer pattern. The second process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the current layer lithography pattern.
[0057] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.
[0058] This application also provides a sampling device for measuring overprinting error. It should be noted that the sampling device for measuring overprinting error in this application can be used to execute the sampling method for measuring overprinting error provided in this application. The sampling device for measuring overprinting error provided in this application is described below.
[0059] Figure 2 This is a schematic diagram of a sampling device for measuring overlay error according to an embodiment of this application. Figure 2As shown, the device includes a first acquisition unit 10, a first determination unit 20, and a sampling unit 30. The first acquisition unit 10 is used to acquire first process information, which is the process information of a target front-layer pattern, and the target front-layer pattern is a front-layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern. The first determination unit 20 is used to determine multiple batches to be sampled based at least on the first process information, wherein the first process information of each target front-layer pattern in the same batch to be sampled is the same. The sampling unit 30 is used to sample the overlay error of each batch to be sampled.
[0060] In the above-mentioned sampling device for measuring overlay error, the first process information of the target front layer pattern is obtained by the first acquisition unit, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; the first determination unit determines multiple batches to be sampled based at least on the first process information, and the first process information of the target front layer pattern in each batch to be sampled is the same; the sampling unit performs sampling measurement on the overlay error of each batch to be sampled. The apparatus described in this application divides the combination of the previous layer lithography pattern and the current layer lithography pattern into multiple sampling batches based on different process information of the previous layer lithography pattern related to the overlay accuracy of the current layer lithography pattern. This ensures that the process information of each previous layer lithography pattern in different sampling batches is different, thus guaranteeing that most combinations of different previous layer lithography patterns and the current layer lithography pattern will be sampled. This avoids the problem of inadequate monitoring of some combination layers, ensures good process monitoring capability, and makes the overlay accuracy more controllable. It effectively alleviates the problem of inadequate monitoring of overlay errors of some combination layers in the lithography process of the prior art.
[0061] Specifically, the aforementioned target front-layer pattern can be a single front-layer lithography pattern that affects the current lithography pattern, or it can include multiple front-layer lithography patterns that affect the current lithography pattern. When the aforementioned target front-layer pattern includes multiple front-layer lithography patterns that affect the current lithography pattern, each front-layer lithography pattern is numbered and analyzed.
[0062] To ensure a relatively simple and accurate acquisition of the first process information, according to a specific embodiment of this application, the first acquisition unit includes a first determining module, a second determining module, and a first acquisition module. The first determining module is used to determine the preceding layer factors affecting the overlay accuracy; the second determining module is used to determine the preceding layer lithography pattern related to the preceding layer factors as the target preceding layer pattern; and the first acquisition module is used to acquire the process information of the target preceding layer pattern to obtain the first process information. By identifying the preceding layer factors affecting the overlay accuracy, the target preceding layer pattern is found relatively quickly, and the found target preceding layer patterns are relatively accurate, all being preceding layer lithography patterns related to the overlay accuracy of the current layer lithography pattern. This ensures that the obtained first process information is relatively accurate, further guaranteeing that the sampled batch obtained based on the first process information can basically include the combination of the preceding layer lithography pattern and the current layer lithography pattern. This further alleviates the problem of inadequate monitoring of overlay errors in some combined layers during existing lithography processes, resulting in poor process monitoring capabilities.
[0063] According to another specific embodiment of this application, the above-mentioned apparatus further includes a second acquisition unit, which is used to acquire second process information before determining multiple batches to be sampled based at least on the first process information. The second process information is the process information of the current layer lithography pattern. Due to the instability of the equipment and the differences between different process equipment, the overlay errors between the various current layer lithography patterns are also different. To further ensure that different combinations of previous layer lithography patterns and current layer lithography patterns are basically sampled, and to minimize the possibility of missed sampling of combinations of previous layer lithography patterns and current layer lithography patterns within a certain period, this application also acquires the second process information of the current layer lithography pattern. This facilitates subsequent batching of products combining previous layer lithography patterns and current layer lithography patterns to be sampled, taking into account both the first and second process information.
[0064] In another specific embodiment of this application, the first determining unit includes a third determining module, which is used to determine multiple batches to be sampled based on the first process information and the second process information. Within the same batch, the second process information of the current layer lithography pattern is identical. By dividing different first process information and different combinations of first process information into different sampling batches, the effect of essentially sampling and testing all combinations of previous and current layer lithography patterns during the lithography process is further achieved.
[0065] In practical applications, those skilled in the art can select any suitable method to determine multiple batches to be sampled based on the first process information and the second process information. In a specific embodiment of this application, the third determining module includes a first dividing submodule and a second dividing submodule. The first dividing submodule is used to divide the final patterns corresponding to different first process information into different first predetermined batches. The final pattern is composed of the overlaid previous lithographic pattern and the current lithographic pattern. The second dividing submodule is used to divide the final patterns corresponding to different second process information in the first predetermined batches into different second predetermined batches, thereby obtaining multiple batches to be sampled.
[0066] Of course, the specific process for determining multiple sampling batches based on the first process information and the second process information is not limited to the process described above. Those skilled in the art can also use other methods to determine multiple sampling batches. For example, the third determining module includes a third dividing submodule and a fourth dividing submodule. The third dividing submodule is used to divide the final patterns corresponding to different second process information into different fifth predetermined batches. The final pattern is composed of the overlaid previous lithographic pattern and the current lithographic pattern. The fourth dividing submodule is used to divide the final patterns corresponding to different first process information in the fifth predetermined batch into different sixth predetermined batches, thereby obtaining multiple sampling batches.
[0067] To further alleviate the problem of inadequate monitoring of overlay errors in some composite layers during photolithography and to further ensure that the overlay accuracy of the photolithography process is more controllable, according to another specific embodiment of this application, the first process information includes first processing time information, and the first division submodule is further used to divide the final patterns corresponding to different first process information into different third predetermined batches; the first division submodule is further used to, according to the first processing time information of each target front layer pattern, to take the final pattern corresponding to the target front layer pattern located in the same first processing cycle in each of the third predetermined batches as a first predetermined batch, thereby obtaining multiple first predetermined batches.
[0068] It should be noted that the aforementioned first processing time period information refers to the start and end times of processing the target front-end graphic. That is, the first processing time period information includes the start and end times of processing the target front-end graphic, and the first processing cycle is a preset time period. The aforementioned target front-end graphics located within the same first processing cycle refer to those whose processing start and end times all fall within the same first processing cycle. For example, when the first processing cycle is from 12:00 to 15:00, multiple target front-end graphics with first processing time periods of 12:05 to 12:55, 12:30 to 13:20, and 13:00 to 15:00 are considered as the aforementioned first predetermined batch.
[0069] Specifically, the aforementioned second process information includes second processing time period information. The aforementioned second division submodule is further used to divide the final patterns corresponding to different second process information in the aforementioned first predetermined batch into different fourth predetermined batches. The aforementioned second division submodule is further used to, based on the second processing time period information of the current layer lithography pattern, to group the final patterns corresponding to the current layer lithography pattern within the same second processing cycle in each of the aforementioned fourth predetermined batches into one aforementioned second predetermined batch, thereby obtaining multiple aforementioned second predetermined batches. This can further reduce the possibility of some combined products of the previous layer and the current layer lithography pattern being skipped, and further ensure that the overlay accuracy of the lithography process is more controllable.
[0070] It should be noted that the aforementioned second processing time period information refers to the start and end times of processing the current layer lithography pattern. That is, the second processing time period information includes the start and end times of processing the current layer lithography pattern, and the second processing cycle is a preset time period. The aforementioned current layer lithography pattern located within the same second processing cycle refers to the current layer lithography pattern whose processing start and end times all fall within the same aforementioned second processing cycle. For example, when the second processing cycle is from 4 PM to 10 PM, multiple current layer patterns with first processing time periods of 5:20 PM to 7:20 PM, 6:00 PM to 8:00 PM, and 9:00 PM to 10:00 PM are considered as the aforementioned second predetermined batch.
[0071] The first processing cycle and the second processing cycle mentioned above can be determined based on the duration of changes in processing parameters that affect the overlay error of the target front layer pattern or the current layer lithography pattern, such as the stability of the machine tool and the adjustment interval of the machine tool parameters. Those skilled in the art can determine the first processing cycle and the second processing cycle based on the actual influencing parameters. Moreover, the first processing cycle and the second processing cycle mentioned above are not fixed, but can be flexibly adjusted according to the actual situation.
[0072] In another specific embodiment, the sampling unit includes a second acquisition module and a sampling module. The second acquisition module is used to acquire the sampling ratios corresponding to different batches to be sampled. The sampling module is used to sample and detect the overlay error of the corresponding batches to be sampled according to the sampling ratios. Sampling different batches to be sampled according to the sampling ratios further enables effective monitoring of overlay errors during the photolithography process, further ensuring that process anomalies can be detected and addressed promptly. Those skilled in the art can set the above-mentioned sampling ratios using a RUN-to-RUN system.
[0073] Furthermore, the aforementioned first process information includes the processing machine information for the target front-end pattern and the corresponding Complex Process Capability Index (Cpk). The aforementioned second acquisition module includes a determination submodule, which is used to determine the corresponding sampling ratio based on the Comprehensive Process Capability Index corresponding to each of the aforementioned batches to be sampled. The Comprehensive Process Capability Index is negatively correlated with the sampling ratio. Cpk is a quantitative reflection of the process level and is an indicator representing the level of process capability. By determining the sampling ratio of the final pattern produced by the corresponding machine based on the Cpk of different machines, it is further ensured that the determined sampling ratio is relatively reasonable, thereby further ensuring good process monitoring capability of the photolithography process, further reducing the generation of defective products, and ensuring good overall quality of the final pattern obtained.
[0074] Specifically, in one implementation, the sampling ratio for the Lot level, corresponding to the Cpk of the processing machine, can be planned as follows:
[0075] When Cpk < 0.67, the sampling ratio can be 20%;
[0076] When Cpk < 1, the sampling ratio can be 10%;
[0077] When Cpk≥1, the sampling ratio can be 5%;
[0078] When Cpk≥1.33, the sampling ratio can be 2%.
[0079] To further ensure that the overlay error of the photolithographically obtained product meets the design requirements and to further achieve effective control over the overlay accuracy of the photolithographically obtained product, in another specific embodiment of this application, the above-mentioned device further includes a second determining unit and a sending unit, wherein the second determining unit is used to determine, after sampling and testing the overlay error of each of the above-mentioned batches to be sampled, a corrected process parameter for reducing the overlay error based on the overlay error; the sending unit is used to send the process parameter to the processing machine.
[0080] In practical applications, those skilled in the art can, based on experience, list the process information of the previous layer lithography pattern that affects the overlay accuracy, and then verify these process information one by one to determine the aforementioned first process information. Alternatively, the first process information of the selected previous layer lithography pattern can be determined by aligning the current layer lithography pattern with the previous layer lithography pattern, such as side circuits, array areas, BEOL (Back End of Line) metal routing, and contact lines. Furthermore, the aforementioned second process information can be determined by analyzing the overlay data of the current layer lithography pattern to predict faults and input sources, such as the machine for previous layer lithography pattern 1 and the photomask for previous layer lithography pattern 2. The process for determining the second process information is the same as the process for determining the first process information, and will not be elaborated here. Of course, the specific methods for determining the aforementioned first and second process information are not limited to the methods described above. Those skilled in the art can flexibly choose appropriate methods according to the actual situation, or flexibly adjust the aforementioned methods. In one specific embodiment, the first process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the target front-layer pattern. The second process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the current layer lithography pattern.
[0081] The sampling device for measuring overlay error includes a processor and a memory. The first acquisition unit, the first determination unit, and the sampling unit are all stored as program units in the memory. The processor executes the program units stored in the memory to achieve the corresponding functions.
[0082] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and adjusting kernel parameters can alleviate the problem of inadequate monitoring of overlay errors in certain composite layers during photolithography in existing technologies.
[0083] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.
[0084] This application provides a computer-readable storage medium storing a program thereon, which, when executed by a processor, implements the above-described sampling method for measuring overlay error.
[0085] This application provides a processor for running a program, wherein the program executes the sampling method for overlay error measurement.
[0086] Specifically, this application provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory. When the computer program is executed by the processor, it performs at least the following steps:
[0087] Step S101: Obtain first process information, wherein the first process information is the process information of the target front layer pattern, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern.
[0088] Step S102: Based on the first process information mentioned above, determine multiple batches to be sampled, wherein the first process information of each of the target front layer patterns in the same batch to be sampled is the same.
[0089] Step S103: The overlay error of each of the above-mentioned batches to be sampled is sampled and tested.
[0090] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.
[0091] This application also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, performs at least the following steps:
[0092] Step S101: Obtain first process information, wherein the first process information is the process information of the target front layer pattern, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern.
[0093] Step S102: Based on the first process information mentioned above, determine multiple batches to be sampled, wherein the first process information of each of the target front layer patterns in the same batch to be sampled is the same.
[0094] Step S103: The overlay error of each of the above-mentioned batches to be sampled is sampled and tested.
[0095] According to another typical embodiment of this application, a lithography system is also provided, the lithography system including a lithography machine and a control device for the lithography machine, the control device including a memory, a processor and a computer program stored in the memory, the computer program being executed by the processor to implement the steps of any of the above methods.
[0096] The aforementioned lithography system includes a lithography machine and its control device, which is used to execute any of the methods described above. Based on different process information of the preceding lithography pattern related to the overlay accuracy of the current lithography pattern, the lithography system divides the combinations of the preceding and current lithography patterns into multiple sampling batches. This ensures that the process information of each preceding lithography pattern in different sampling batches is different, thus guaranteeing that most combinations of different preceding and current lithography patterns will be sampled. This avoids the problem of inadequate monitoring of some combination layers, ensuring good process monitoring capabilities and controllable overlay accuracy, effectively alleviating the problem of inadequate monitoring of overlay errors in some combination layers during the lithography process of existing technologies.
[0097] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.
[0098] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units described above can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.
[0099] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0100] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.
[0101] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.
[0102] As can be seen from the above description, the embodiments of this application achieve the following technical effects:
[0103] 1) In the sampling method for measuring overlay error described above in this application, firstly, the first process information of the target front-layer pattern is obtained, wherein the target front-layer pattern is the front-layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; then, at least based on the first process information, multiple sampling batches are determined, wherein the first process information of the target front-layer pattern in each sampling batch is the same; finally, the overlay error of each of the above sampling batches is sampled. The method described above in this application, based on different process information of the front-layer lithography pattern related to the overlay accuracy of the current layer lithography pattern, divides the combination of the front-layer lithography pattern and the current layer lithography pattern into multiple sampling batches, so that the process information of each front-layer lithography pattern in different sampling batches is different. This ensures that the combination of different front-layer lithography patterns and the current layer lithography pattern will be sampled, avoiding the problem of inadequate monitoring of some combination layers, ensuring good process monitoring capability, and relatively controllable overlay accuracy, effectively alleviating the problem of inadequate monitoring of overlay error of some combination layers in the lithography process of the prior art.
[0104] 2) In the sampling device for measuring overlay error described above in this application, the first process information of the target front layer pattern is obtained by the first acquisition unit, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; the first determination unit determines multiple batches to be sampled based at least on the first process information, and the first process information of the target front layer pattern in each batch to be sampled is the same; the sampling unit performs sampling measurement on the overlay error of each batch to be sampled. The sampling device described in this application divides the combination of the previous layer lithography pattern and the current layer lithography pattern into multiple sampling batches based on different process information of the previous layer lithography pattern related to the overlay accuracy of the current layer lithography pattern. This ensures that the process information of each previous layer lithography pattern in different sampling batches is different, thus guaranteeing that most combinations of different previous layer lithography patterns and the current layer lithography pattern will be sampled. This avoids the problem of inadequate monitoring of some combination layers, ensures good process monitoring capability, and makes the overlay accuracy more controllable. It effectively alleviates the problem of inadequate monitoring of overlay errors of some combination layers in the lithography process of the prior art.
[0105] 3) The lithography system described in this application includes a lithography machine and its control device, wherein the control device is used to execute any of the methods described above. Based on different process information of the previous layer lithography pattern related to the overlay accuracy of the current layer lithography pattern, the lithography system divides the combination of the previous layer lithography pattern and the current layer lithography pattern into multiple sampling batches, such that the process information of each previous layer lithography pattern in different sampling batches is different. This ensures that almost all combinations of different previous layer lithography patterns and the current layer lithography pattern are sampled, avoiding the problem of inadequate monitoring of some combination layers, ensuring good process monitoring capability, and relatively controllable overlay accuracy. This effectively alleviates the problem of inadequate monitoring of overlay errors of some combination layers in the lithography process of the prior art.
[0106] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A sampling method for measuring overlay error, characterized in that, include: Obtain first process information, which is the process information of the target front layer pattern, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern; Based on the first process information, at least a plurality of batches to be sampled are determined, wherein the first process information of each of the target front layer patterns in the same batch to be sampled is the same; The overlay error of each of the batches to be sampled was measured separately. Before determining a plurality of batches to be sampled based at least on the first process information, the method further includes: Obtain second process information, which is the process information of the current layer photolithography pattern; Based on the first process information, at least several batches to be sampled are identified, including: Based on the first process information and the second process information, multiple batches to be sampled are determined, and in the same batch to be sampled, the second process information of the current layer lithography pattern is the same; The overprinting error of each of the aforementioned batches to be sampled was tested, including: Obtain the sampling ratios corresponding to the different batches to be sampled; The overlay error of the corresponding batch to be sampled is sampled and detected according to the sampling ratio. The first process information includes the processing machine information of the target front-end pattern and the comprehensive process capability index corresponding to the processing machine, and obtains the sampling ratio corresponding to different batches to be sampled, including: The sampling ratio is determined based on the comprehensive process capability index corresponding to each batch to be sampled, and the comprehensive process capability index is negatively correlated with the sampling ratio.
2. The method of claim 1, wherein, Obtain first-process information, including: Identify the preceding factors that affect the overlay accuracy; The front-layer lithographic pattern related to the aforementioned front-layer factors is identified as the target front-layer pattern; The process information of the target front-layer pattern is obtained to obtain the first process information.
3. The method of claim 1, wherein, Based on the first process information and the second process information, a plurality of the batches to be sampled are determined, including: The final patterns corresponding to different first process information are divided into different first predetermined batches, wherein the final pattern is composed of the overlaid previous layer photolithography pattern and the current layer photolithography pattern; The final graphics corresponding to different second process information in the first predetermined batch are divided into different second predetermined batches to obtain multiple batches to be sampled.
4. The method of claim 3, wherein, The first process information includes first processing time period information, which divides the final graphics corresponding to different first process information into different first predetermined batches, including: The final graphics corresponding to different first process information are divided into different third predetermined batches; Based on the first processing time period information of each target front layer graphic, the final graphic corresponding to the target front layer graphic that is located in the same first processing cycle in each third predetermined batch is taken as a first predetermined batch, thus obtaining multiple first predetermined batches.
5. The method of claim 3, wherein, The second process information includes second processing time information, which divides the final graphics corresponding to different second process information in the first predetermined batch into different second predetermined batches, including: The final patterns corresponding to different second process information in the first predetermined batch are divided into different fourth predetermined batches; Based on the second processing time information of the current layer lithography pattern, the final pattern corresponding to the current layer lithography pattern in each of the fourth predetermined batches that is located in the same second processing cycle is taken as a second predetermined batch, thus obtaining multiple second predetermined batches.
6. The method according to any one of claims 1 to 5, characterized in that, After sampling and measuring the overprinting error of each of the batches to be sampled, the method further includes: Based on the overlay error, determine the corrected process parameters for reducing the overlay error; Send the process parameters to the processing machine.
7. The method according to any one of claims 1 to 5, characterized in that, The first process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the target front layer pattern.
8. The method according to any one of claims 3 to 5, characterized in that, The second process information includes at least one of the following: machine information, photomask information, processing path information, and the number of overlay steps for the current layer photolithography pattern.
9. A sampling device for overlay metrology for implementing the sampling method for overlay metrology according to any one of claims 1 to 8, characterized in that include: The first acquisition unit is used to acquire first process information, wherein the first process information is the process information of the target front layer pattern, and the target front layer pattern is the front layer lithography pattern that affects the overlay accuracy of the current layer lithography pattern. The first determining unit is configured to determine multiple batches to be sampled based at least on the first process information, wherein the first process information of each of the target front layer patterns in the same batch to be sampled is the same. The sampling unit is used to sample and test the overprinting error of each of the batches to be sampled.
10. An electronic device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1 to 8.
11. A computer-readable storage medium having a computer program stored thereon, 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 to 8.
12. A photolithography system, characterized in that, include: Photolithography machine; The control device for the lithography machine includes a memory, a processor, and a computer program stored in the memory. When the computer program is executed by the processor, it implements the steps of the method according to any one of claims 1 to 8.