Monitoring method for etching cavity
By monitoring the overlay accuracy data of the etching cavity after development and after etching, and calculating the ADI-AEI M+3S value, the problem of chip yield decline caused by the difference in etching cavity equipment was solved, and the stability monitoring and yield protection of the etching cavity were realized.
Patent Information
- Application Number
- CN202511695368.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-02-27
AI Technical Summary
In the semiconductor mass production process, the inconsistency in overlay precision in the wafer edge area due to the equipment differences of the etching cavity affects the chip yield and is difficult to predict and control in the mass production stage.
By monitoring the overlay accuracy data of the etching cavity after development and after etching, the ADI-AEI M+3S value is calculated, anomaly notifications are generated to identify abnormal cavities, optimize the measurement conditions of CD measurement equipment, and ensure the reliability of monitoring results.
Timely identification and handling of abnormal etching cavities can reduce yield loss and improve the stability of etching cavities and the reliability of monitoring results.
Smart Images
Figure CN121578600A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing technology, and more specifically to a monitoring method for etching cavities. Background Technology
[0002] In semiconductor mass production, equipment differences (machine variations) can exist between different process chambers. For example, differences in the state of the edge ring within an etching chamber (such as wear levels or assembly precision variations) can lead to inconsistencies in the overlay performance (OVL) of the wafer edge region. In the early R&D phase, because the etching chamber used is relatively simple and the process conditions are stable, the OVL performance after etching is also relatively stable. However, once mass production begins, if multiple chambers operate in parallel, equipment differences can cause a series of serious impacts. For example, the chip yield in the wafer edge region may decrease, and the process maintenance difficulty of subsequent functional layers that need to be aligned based on this layer will also increase significantly.
[0003] Taking the mass production of advanced process nodes (such as 7nm and below) as an example, after the final etching of the POMDL layer and the wide polysilicon layer is completed, the overlay accuracy after etching will be significantly different due to the different etching cavities used.
[0004] The post-etching overlay accuracy (AEI OVL Map) of these two critical layers (such as the POMDL layer and the wide polysilicon layer) is often unpredictable during the photolithography stage (PH stage) and only becomes apparent after the etching process is complete. Even if the post-development overlay accuracy (ADI OVL) is controlled very well, if the wafer passes through an etching chamber in poor condition, it will still lead to a decrease in chip yield. Summary of the Invention
[0005] This application provides a monitoring method for etching cavities, which can monitor the stability of the etching cavity in a timely manner and reduce yield loss.
[0006] This application provides a monitoring method for an etching cavity, including: S1: Provide the current batch of wafers that have undergone the development process, wherein each wafer in the current batch has had its overlay accuracy data collected by a CD measurement device after development; S2: Distribute the current batch of wafers into several etching cavities; S3: Use the etching cavity to perform an etching process on the allocated wafer; S4: Use CD measurement equipment to collect the overlay accuracy data after etching for each wafer; S5: Input the wafer ID and etching cavity number corresponding to the overlay accuracy data after development and the overlay accuracy data after etching into the data processing device; S6: Based on the input overlay accuracy data after development and overlay accuracy data after etching, the data processing device obtains the ADI-AEI M+3S value corresponding to the etching cavity. S7: When the ADI-AEI M+3S value of the target etching cavity exceeds the preset threshold, the data processing device generates an abnormal notification for the target etching cavity, which is any one of the etching cavities.
[0007] In some embodiments, prior to step S1, the method further includes: Provide test wafers; Several sets of measurement data of the test wafer were obtained using CD measurement equipment. Each set of measurement data includes overlay accuracy data after development and overlay accuracy data after etching. The measurement conditions of different sets of measurement data are different. Using data processing equipment, the linear correlation between the overlay accuracy data after development and the overlay accuracy data after etching under different measurement conditions was obtained based on each set of measurement data. Based on the degree of linear correlation, determine the optimal measurement conditions; Set the equipment parameters of the CD measurement device according to the optimal measurement conditions.
[0008] In some embodiments, the measurement conditions involve device parameters including the wavelength, polarization, and energy of the CD measurement device.
[0009] In some embodiments, in the step of determining the optimal measurement conditions based on the degree of linear correlation, the measurement conditions of the measurement data with the degree of linear correlation closest to 1 are selected as the optimal measurement conditions.
[0010] In some embodiments, in step S7, the threshold is set within the range of [4, 5].
[0011] The technical solution of this application has at least the following advantages: 1. By monitoring the overlay accuracy data after development of the wafer and the overlay accuracy data after etching of the wafer in different etching cavities, it is possible to determine whether there are any abnormalities in the etching cavity based on the ADI-AEI M+3S value of different etching cavities. This allows for timely monitoring of the stability of the etching cavity and reduces yield loss. 2. By optimizing the measurement conditions of the CD measurement machine by measuring the linear correlation between the overlay accuracy data after development and the overlay accuracy data after etching, the reliability of the monitoring results is improved. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0013] Figure 1 This is a flowchart of a monitoring method for an etching cavity provided in an exemplary embodiment of this application; Figure 2 This is a possible AEI-ADI MAP diagram provided in an exemplary embodiment of this application; Figure 3 This is a data point distribution map obtained under one possible measurement condition, provided by an exemplary embodiment of this application; Figure 4 This is a data point distribution map obtained under another possible measurement condition provided by an exemplary embodiment of this application. Detailed Implementation
[0014] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0015] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0016] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0017] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0018] This application provides a monitoring method for an etching cavity, referring to... Figure 1 The method includes the following steps: S1: Provides wafers from the current batch that have undergone the development process. Each wafer in the current batch has had its overlay accuracy data collected after development using a CD measurement device.
[0019] In practice, the current batch of wafers is the batch of wafers currently being produced during the mass production process. The current batch of wafers has already undergone the development process, and the ADI OVL (Advanced Die-In, Die-Out) data of each wafer has been collected using CD measurement equipment.
[0020] S2: Assign the current batch of wafers to several etching cavities.
[0021] In practice, all wafers in the current batch can be allocated to several etching cavities used in mass production, based on production needs. During this process, the correspondence between wafers and etching cavities is established through data recording and other methods.
[0022] S3: Use an etching chamber to perform an etching process on the assigned wafer.
[0023] In practice, etching chambers are used to perform etching processes on the allocated wafers according to the etching process during mass production.
[0024] S4: Use CD measurement equipment to collect the overlay accuracy data after etching for each wafer.
[0025] During implementation, CD measurement equipment was used to collect the etching accuracy (AEI OVL) data for each wafer.
[0026] S5: Input the wafer ID and etching cavity number corresponding to the overlay accuracy data after development and the overlay accuracy data after etching into the data processing equipment.
[0027] During implementation, the wafer ID and etching cavity number corresponding to the overlay accuracy data after development and after etching are entered into the data processing equipment. Specifically, for each etching cavity, its etching cavity number is associated with the wafer ID of the wafer to which that etching cavity is assigned; and for each wafer, its wafer ID is associated with both the overlay accuracy data after development and the overlay accuracy data after etching.
[0028] S6: Based on the input overlay accuracy data after development and overlay accuracy data after etching, the data processing device obtains the ADI-AEI M+3S value corresponding to the etching cavity.
[0029] During implementation, the data processing equipment extracts the ADI-AEI deviation data of all wafers in the current batch processed by each etching cavity, and automatically calculates the average (M) and standard deviation (S) of all the ADI-AEI deviation data, thereby calculating the ADI-AEI M+3S value corresponding to that etching cavity. After completing the calculation of the data corresponding to all etching cavities, the ADI-AEI M+3S value corresponding to each etching cavity can be obtained.
[0030] S7: When the ADI-AEI M+3S value of the target etching cavity exceeds the preset threshold, the data processing device generates an abnormal notification for the target etching cavity, which can be any one of the etching cavities.
[0031] During implementation, the data processing equipment compares the ADI-AEI M+3S value corresponding to each etching cavity with a preset threshold. When it detects that the ADI-AEI M+3S value of a target etching cavity exceeds the preset threshold, the data processing equipment generates an anomaly notification for the target etching cavity. For example, an alarm can be triggered through a real-time fault detection and classification system (FDC) to automatically lock the target etching cavity, causing it to suspend receiving new work orders, thus facilitating timely troubleshooting and resolution by production line engineers.
[0032] Furthermore, the threshold value mentioned above can be set within the range of [4, 5]. (Refer to...) Figure 2 The images in the second row are AEI-ADI MAP images of different etching cavities, where 55A, 54A, and 32C are the etching cavity numbers. Figure 2 As can be seen, the ADI-AEI M+3S value of the etching cavity corresponding to 55A reached 8.3615, which exceeded the threshold, indicating that there is an anomaly in the etching cavity corresponding to 55A.
[0033] Furthermore, prior to step S1 above, the following steps may also be included: Test wafers are provided.
[0034] Several sets of measurement data were acquired using CD measurement equipment. Each set of measurement data included overlay accuracy data after development and overlay accuracy data after etching. The measurement conditions for different sets of measurement data were different.
[0035] In implementation, after the development process of the test wafer, the overlay accuracy data after development can be obtained using a CD measurement device under measurement conditions A1, A2, A3, B1, B2, B3, C1, C2, and C3. After the etching process of the test wafer, the overlay accuracy data after etching can be obtained under measurement conditions A1, A2, A3, B1, B2, B3, C1, C2, and C3. The overlay accuracy data after development and the overlay accuracy data after etching obtained under the same measurement conditions constitute a set of measurement data. The measurement conditions mentioned above are not fixed; in other embodiments, different numbers and schemes of measurement conditions can also be used.
[0036] The measurement conditions involve equipment parameters including the wavelength, polarization, and energy of the CD measurement equipment. For example, the difference between measurement conditions A1, A2, and A3 lies in the wavelength setting, the difference between measurement conditions B1, B2, and B3 lies in the polarization setting, and the difference between measurement conditions C1, C2, and C3 lies in the energy setting.
[0037] Using data processing equipment, the linear correlation between the overlay accuracy data after development and the overlay accuracy data after etching under different measurement conditions was obtained based on each set of measurement data.
[0038] In practice, the data processing equipment, based on each set of measurement data, obtains the linear correlation between the post-development overlay accuracy data and the post-etching overlay accuracy data under different measurement conditions. For example, for any set of measurement data, the data processing equipment can generate a data point distribution map with the post-development overlay accuracy data as the x-axis and the post-etching overlay accuracy data as the y-axis. Then, by fitting the data, it obtains a fitting formula with the post-development overlay accuracy data as the independent variable and the post-etching overlay accuracy data as the dependent variable, and obtains the linear correlation R^2 between the post-development overlay accuracy data and the post-etching overlay accuracy data for that set of measurement data. (Refer to...) Figure 3 and Figure 4 It shows the distribution of data points obtained under two measurement conditions, where, Figure 3 The corresponding linear correlation coefficient was 0.06384. Figure 4The corresponding linear correlation is 0.327. The closer the linear correlation R^2 is to 1, the better the correlation between the overlay accuracy data after development and the overlay accuracy data after etching.
[0039] The optimal measurement conditions are determined based on the degree of linear correlation.
[0040] In practice, the data processing equipment can identify the degree of linear correlation R^2 obtained under different measurement conditions, and select the measurement conditions of the measurement data with the degree of linear correlation closest to 1 as the optimal measurement conditions.
[0041] Set the equipment parameters of the CD measurement device according to the optimal measurement conditions.
[0042] During implementation, the equipment parameters of the CD measurement device can be set according to the optimal measurement conditions to ensure the reliability of subsequent monitoring results.
[0043] The monitoring method for etching cavities provided in this application has two advantages. First, by monitoring the overlay accuracy data of the wafer after development and the overlay accuracy data of the wafer after etching in different etching cavities, it is possible to determine whether there are any abnormalities in the etching cavity based on the ADI-AEI M+3S values of different etching cavities. This allows for timely monitoring of the stability of the etching cavity and reduces yield loss. Second, by optimizing the measurement conditions of the CD measurement machine through the linear correlation between the overlay accuracy data after development and the overlay accuracy data after etching, the reliability of the monitoring results is improved.
[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.
Claims
1. A monitoring method for an etching cavity, characterized in that, include: S1: Provide the current batch of wafers that have undergone the development process, wherein each wafer in the current batch has had its overlay accuracy data collected by a CD measurement device after development; S2: Distribute the current batch of wafers into several etching cavities; S3: Use the etching cavity to perform an etching process on the allocated wafer; S4: Use CD measurement equipment to collect the overlay accuracy data after etching for each wafer; S5: Input the wafer ID and etching cavity number corresponding to the overlay accuracy data after development and the overlay accuracy data after etching into the data processing device; S6: Based on the input overlay accuracy data after development and overlay accuracy data after etching, the data processing device obtains the ADI-AEI M+3S value corresponding to the etching cavity. S7: When the ADI-AEI M+3S value of the target etching cavity exceeds the preset threshold, the data processing device generates an abnormal notification for the target etching cavity, which is any one of the etching cavities.
2. The monitoring method for an etching cavity according to claim 1, characterized in that, Prior to step S1, the method further includes: Provide test wafers; Several sets of measurement data of the test wafer were obtained using CD measurement equipment. Each set of measurement data includes overlay accuracy data after development and overlay accuracy data after etching. The measurement conditions of different sets of measurement data are different. Using data processing equipment, the linear correlation between the overlay accuracy data after development and the overlay accuracy data after etching under different measurement conditions was obtained based on each set of measurement data. Based on the degree of linear correlation, determine the optimal measurement conditions; Set the equipment parameters of the CD measurement device according to the optimal measurement conditions.
3. The monitoring method for an etching cavity according to claim 2, characterized in that, The measurement conditions involve equipment parameters including the wavelength, polarization, and energy of the CD measurement equipment.
4. The monitoring method for an etching cavity according to claim 2, characterized in that, In the step of determining the optimal measurement conditions based on the degree of linear correlation, the measurement conditions of the measurement data with the degree of linear correlation closest to 1 are selected as the optimal measurement conditions.
5. The monitoring method for an etching cavity according to claim 1, characterized in that, In step S7, the threshold is set within the range of [4, 5].