Silicon wafer testing method and silicon wafer testing system

Abstract

The application provides a silicon wafer testing method, which comprises the following steps: performing a standard sample test to obtain standard sample test data; the standard sample test is performed on a standard sample stage; when the standard sample test data indicates that the probe does not need to be replaced, performing a sample test to obtain sample test data; the sample test is performed on a sample stage; wherein the size of the standard sample is smaller than the size of the sample, and the size of the standard sample stage is smaller than the size of the sample stage. The application judges the state of the probe through the standard sample test data, and continues the sample test when the state of the probe meets the requirements, thereby monitoring the state of the probe and improving the accuracy of the sample test. The standard sample test can be completed in a smaller range, thereby saving time and space and improving the testing efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of silicon wafer surface detection, and in particular to a silicon wafer testing method and a silicon wafer testing system. BACKGROUND

[0002] In the semiconductor industry, the testing precision of the surface roughness of a silicon wafer directly affects the yield and performance in the subsequent chip manufacturing process. Therefore, an accurate roughness testing method is crucial to ensure the quality of the silicon wafer. Currently, an atomic force microscope (AFM) is often used for testing the surface roughness of a silicon wafer. The AFM obtains high-precision roughness data by contacting a probe with the surface of the silicon wafer and scanning the surface topography.

[0003] However, the accuracy of the AFM testing is significantly affected by the state of the probe. As the testing proceeds, the probe may be aged, worn, or contaminated due to long-term use, thereby affecting the testing results. Since the change in the state of the probe is usually not directly noticeable, and the intrinsic vibration frequency curve of the probe does not change significantly in the surface scanning, the aging of the probe may gradually accumulate during the testing, eventually leading to a decrease in the measurement accuracy. In the related art, there is a lack of a monitoring mechanism for the state of the probe, which makes it difficult to fully guarantee the accuracy of the testing.

[0004] Therefore, the present application provides a silicon wafer testing method and a silicon wafer testing system to improve the related art. SUMMARY

[0005] The present application aims to provide a silicon wafer testing method and a silicon wafer testing system to monitor the state of a probe and improve the accuracy of sample testing.

[0006] The present application achieves the above-mentioned purpose by adopting the following technical solutions:

[0007] In a first aspect, the present application provides a silicon wafer testing method, which includes: performing a standard sample test to obtain standard sample test data; the standard sample test is performed on a standard sample stage; in a case where the standard sample test data indicates that a probe does not need to be replaced, performing a sample test to obtain sample test data; the sample test is performed on a sample stage; wherein the size of the standard sample is smaller than the size of the sample, and the size of the standard sample stage is smaller than the size of the sample stage.

[0008] In some embodiments, the process of determining whether the probe needs to be replaced by using the standard sample test data includes: in a case where the standard sample test data is within a target value range, it is determined that the standard sample test data indicates that the probe does not need to be replaced; or in a case where the standard sample test data is not within the target value range, it is determined that the standard sample test data indicates that the probe needs to be replaced.

[0009] In some embodiments, the method further comprises: in the case that the standard sample test data indicates that the probe needs to be replaced, repeating the steps of replacing the probe and performing the standard sample test until the latest obtained standard sample test data indicates that the probe does not need to be replaced.

[0010] In some embodiments, the method further comprises: in the case that the sample test is not completed, determining whether the standard sample test needs to be performed again; in the case that the standard sample test needs to be performed again, performing the standard sample test again.

[0011] In some embodiments, the method further comprises: in the case that the standard sample test does not need to be performed again, continuing to perform the sample test.

[0012] In some embodiments, the method further comprises: in the case that the sample test is completed, ending the test.

[0013] In some embodiments, the method further comprises: setting the test point and / or scanning parameter corresponding to the standard sample test; and / or, setting the test point and / or scanning parameter corresponding to the sample test.

[0014] In some embodiments, the scanning parameter comprises one or more of test area, scanning speed and scanning resolution.

[0015] In a second aspect, the present application provides a silicon wafer test system, the system comprising: a standard sample stage; a sample stage; a control module configured to perform any of the above methods.

[0016] In some embodiments, the height of the standard sample stage matches the height of the sample stage.

[0017] The application provides a silicon wafer testing method and a silicon wafer testing system. The probe state is determined by using the sample testing data, and the sample testing is continued when the probe state meets the requirements. First, the sample testing data is obtained by performing sample testing on the sample stage. The sample data reflects the accuracy of the current probe state. When the sample testing data indicates that the probe does not need to be replaced (for example, the probe state does not change significantly and meets the requirements), it means that the probe state is good, and the sample testing can be performed. At this time, the sample testing will start to be performed, and the sample testing data is obtained on the sample stage. The size of the sample used is smaller than the size of the sample, and the size of the sample stage is smaller than the size of the sample stage, so the sample testing can be performed in a smaller range, ensuring the flexibility of the sample testing and the efficiency of the overall testing process. During the whole testing process, the sample testing result is used as a verification mechanism to ensure that the problem is found and adjusted in time when the probe state is poor, so as to ensure the accuracy of the sample testing. The application can monitor the probe state by combining the sample testing and the sample testing, and reduce the decrease of the measurement accuracy caused by the aging, wear and pollution of the probe. Only when the sample testing indicates that the probe does not need to be replaced, the sample testing can continue, so as to improve the accuracy and stability of the silicon wafer roughness testing. Secondly, since the size of the sample is smaller than the size of the sample, and the size of the sample stage is smaller than the size of the sample stage, the sample testing can be completed in a smaller range, saving time and space, and improving the testing efficiency. In addition, the effective monitoring of the sample testing data enables the replacement of the probe to be automatically performed, reduces the manual intervention, and improves the automation level and work efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0018] The application will be further described below in combination with the drawings and specific embodiments.

[0019] Figure 1 FIG. 1 is a structural schematic diagram of a sample stage and a sample stage provided by an embodiment of the application.

[0020] Figure 2a FIG. 2 is a cross-sectional schematic diagram (front view) of a sample stage provided by an embodiment of the application.

[0021] Figure 2b FIG. 3 is a structural schematic diagram (top view) of a sample stage provided by an embodiment of the application.

[0022] Figure 3 FIG. 4 is a flowchart of a sample testing provided by an embodiment of the application.

[0023] Figure 4 FIG. 5 is a flowchart of a sample testing provided by an embodiment of the application.

[0024] In the figure: 100, sample stage; 101, groove; 200, sample stage. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be apparently and completely described in combination with the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person skilled in the art without any creative work fall within the scope of protection of the present application.

[0026] In the description of the embodiments of the present application, it should be understood that the terms "first", "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0027] The accuracy of AFM (Atomic Force Microscope) test is highly dependent on the state of the needle tip. As the needle tip travels a longer distance during the test, the needle tip is worn and aged under the action of force, or adheres to foreign matter, resulting in a decrease in test accuracy. The state of the probe needs to be detected, and the failed probe needs to be replaced in time to ensure the accuracy of the test. In the test of the roughness of a silicon wafer, the intrinsic vibration frequency curve of the probe often does not change significantly, but the accuracy of the roughness measurement is affected by the aging of the probe, and the measured value is significantly smaller.

[0028] In the test of a silicon wafer, the aging of the probe can cause a large error in the test result due to the extremely small surface roughness of the silicon wafer. The test accuracy is deteriorated, for example, the measured value is smaller than the true value.

[0029] In the automated test process for a super flat sample, there is a lack of detection means for the state of the probe, and it is difficult to ensure the accuracy of the test.

[0030] Referring to Figure 1 , Figure 2a and Figure 2b , Figure 1 is a structural schematic diagram of a sample stage 200 provided by an embodiment of the present application, Figure 2a is a sectional schematic diagram (front view) of a sample stage 200 provided by an embodiment of the present application, Figure 2b is a structural schematic diagram (top view) of a sample stage 200 provided by an embodiment of the present application.

[0031] The embodiment of the present application provides a silicon wafer testing method, which comprises: performing a standard sample test to obtain standard sample test data; the standard sample test is performed on a standard sample stage 100; in the case that the standard sample test data indicates that a probe does not need to be replaced, performing a sample test to obtain sample test data; the sample test is performed on a sample stage 200; wherein the size of the standard sample is smaller than the size of the sample, and the size of the standard sample stage 100 is smaller than the size of the sample stage 200.

[0032] Wherein, the sample is a silicon wafer sample. The above embodiment can realize probe state monitoring. In a related silicon wafer testing system, a standard sample stage 100 is added, as shown in Figure 1 As an example, the height of the standard sample stage 100 can be the same as or similar to the height of the sample stage 200, and the standard sample stage 100 can place a standard sample with a certain size. For example, the central part of the standard sample stage 100 has a groove 101 for fixing a sample, and the size of the groove 101 (i.e., a clamping groove) can match the size of the standard sample, and the height of the groove 101 can match the thickness of the standard sample.

[0033] Referring to Figure 3 and Figure 4 , Figure 3 is a flowchart of a standard sample test provided by the embodiment of the present application, Figure 4 is a flowchart of a sample test provided by the embodiment of the present application.

[0034] As shown in Figure 3 and Figure 4 , before performing the standard sample test and / or the sample test, or in the process of performing the test, or after the test is completed, the related test parameters (for example, test points, scanning parameters) can be set or adjusted. As an example, the test parameters can be set when creating a test strategy (for example, a standard sample test strategy, a sample test strategy). In some embodiments, the method can further comprise: setting the test points and / or scanning parameters corresponding to the standard sample test; and / or, setting the test points and / or scanning parameters corresponding to the sample test. Wherein, the test points refer to the positions of the test points.

[0035] In some embodiments, the scanning parameters can comprise one or more of a test area, a scanning rate and a scanning resolution.

[0036] In the above embodiment, the standard sample test can be a standard sample roughness test, and the sample test can be a sample roughness test.

[0037] For example, a first step is to prepare a standard sample. For example, a standard sample silicon wafer can be cut to obtain a silicon wafer slice of a certain size (e.g., 20 mm x 20 mm) as a standard sample. Next, the standard sample is placed on the standard sample stage 100. Then, a standard sample test recipe (i.e., strategy) is established, the position (i.e., test point) of the standard sample test is determined, the scanning parameters are determined, the standard sample test is scanned 10 times, and the standard sample test recipe is saved. After that, the standard sample test recipe is run. After the standard sample test is completed, standard sample test data is obtained. According to the test requirements, the lower limit of the probe state deterioration can be determined according to this data (i.e., standard sample test data). The standard sample test data can reflect the probe state, and the continuously measured standard sample data can reflect the regularity of the probe state.

[0038] In some embodiments, the process of determining whether the probe needs to be replaced using the standard sample test data can include: in the case that the standard sample test data is within a target value range, it is determined that the standard sample test data indicates that the probe does not need to be replaced; or in the case that the standard sample test data is not within the target value range, it is determined that the standard sample test data indicates that the probe needs to be replaced.

[0039] In some embodiments, the target value range corresponding to the standard sample test data can be 0.225 nm to 0.238 nm.

[0040] In some embodiments, the method can further include: in the case that the standard sample test data indicates that the probe needs to be replaced, repeating the steps of replacing the probe and performing the standard sample test until the latest obtained standard sample test data indicates that the probe does not need to be replaced.

[0041] In the above embodiments, the automatic program of performing the standard sample test is performed according to the following process after the standard sample is prepared. First, the standard sample is placed. Next, a standard sample test recipe is established, the position (i.e., test point) of the standard sample test is determined, the scanning parameters are determined, and the standard sample test recipe is saved. Then, the automatic running is started, and the standard sample test data is obtained. If the test value (i.e., standard sample test data) is not within the target value range (e.g., less than the minimum value of the target value range), the probe is automatically replaced, and the step of starting the automatic running is jumped to. If the standard sample test result is qualified (i.e., the standard sample test data is within the target value range), the sample test is performed.

[0042] For example, in a specific application scenario, the standard sample test process is performed according to the following steps S101-S105.

[0043] S101: Prepare a standard sample. A standard sample silicon wafer is cut to obtain a standard sample slice (i.e., standard sample) with a size of 20 x 20 mm.

[0044] S102: Place the standard sample, and align the standard sample with the groove 101 of the standard sample stage 100. For example, pick up the standard sample with tweezers and place it on the standard sample stage 100, so that the standard sample completely matches the groove 101 of the standard sample stage 100.

[0045] S103: Establish a standard sample test recipe, and determine a test point: select a fixed point (for example, the center point of the standard sample); set a scanning scheme: repeatedly scan the fixed point of the standard sample, 5 times for each group, and repeat for 20 groups. Set the scanning parameters: set the test area to 2.5 x 2.5 μm, set the scanning rate to 0.5 Hz, and set the scanning resolution pixel to 256 x 256.

[0046] S104: Run the standard sample test recipe. For example, start automatic running, and test the fixed point (i.e., the test point) of the standard sample slice.

[0047] S105: After the standard sample test is completed, obtain the standard sample test data. If the test value (i.e., the standard sample test data) is not within the target value range (for example, less than the minimum value of the target value range), replace the probe, and jump to step S104; if the standard sample test result is qualified (i.e., the standard sample test data is within the target value range), continue to perform sample testing.

[0048] In the above embodiment, according to the test requirements, the lower limit of the probe state deterioration can be determined according to the standard sample test data. As an example, assuming that the target value range corresponding to the standard sample test data is 0.225 nm to 0.238 nm, if the standard sample test data is 0.230 nm, it is determined that the standard sample test data indicates that the probe does not need to be replaced; if the standard sample test data is 0.224 nm, it is determined that the standard sample test data indicates that the probe needs to be replaced.

[0049] In the above standard sample test process, the standard sample test data (for example, the monitoring data of the standard sample roughness value) is obtained, as shown in Table 1. The data (i.e., the standard sample test data) can reflect the state of the probe. By accurately monitoring the state of the probe and replacing the probe in time, the accuracy of the test is improved. At the same time, the probe can be replaced automatically, and the test efficiency is improved. In Table 1, the range is the difference between the maximum value and the minimum value. The corresponding standard sample test specifications in Table 1 are shown in Table 2. In Table 2, the control limit is a criterion for judging whether there is an abnormal reason in the production process or procedure. UCLx is the maximum value of the target value range corresponding to the standard sample test data, and LCLx is the minimum value of the target value range corresponding to the standard sample test data.

[0050] Table 1

[0051]

[0052] Table 2

[0053]

[0054] As Figure 4 shown in some embodiments, the method can further include: determining whether the standard sample test needs to be performed again in the case that the sample test is not completed; performing the standard sample test again in the case that the standard sample test needs to be performed again.

[0055] In some embodiments, the method can further include: continuing to perform the sample test in the case that the standard sample test does not need to be performed again.

[0056] In some embodiments, the method can further include: ending the test in the case that the sample test is completed.

[0057] For example, in one specific application scenario, the sample test procedure is performed according to the following steps S201-S207.

[0058] Step S201: creating a sample test recipe (i.e., strategy), setting test points (a total of 25 points), scanning parameters, and saving the recipe. In the scanning parameters, the test area is set to 2.5x2.5 pm, the scanning rate is set to 0.5 Hz, and the scanning resolution (pixel) is set to 256x256.

[0059] Step S202: performing the standard sample test recipe.

[0060] Step S203: placing the sample or replacing the sample.

[0061] Step S204: performing the sample test.

[0062] Step S205: determining whether the sample test is completed (i.e., whether all samples are tested); if the sample test is completed, jumping to step S207; if the sample test is not completed, performing step S206.

[0063] Step S206: determining whether the standard sample test needs to be performed again; if not, repeating steps S203-S204; if the standard sample test needs to be performed again, repeating steps S202-S204.

[0064] Step S207: ending the test.

[0065] Table 3

[0066]

[0067] From the test results in Table 3, after testing slot5, slot12, slot23, the system automatically replaces the probe and completes the test because the test data of the sample exceeds the lower limit of the specification (i.e., less than the minimum value of the target value range). In this way, the test efficiency is significantly improved, the standard deviation of the test sample is less than 1%, and the test stability and accuracy are improved. The slot refers to the carrying position of the silicon wafer in the carrier.

[0068] In the sample test of the silicon wafer, due to the extremely small surface roughness of the silicon wafer, the aging of the probe can cause a large error in the test result, specifically, the test accuracy is poor, and the test value is less than the true value. The above embodiment realizes rapid automatic monitoring of the probe state by increasing the specially designed sample carrier 100 and the automatic test program (i.e., the automatic sample test program), which guarantees the accuracy of the sample test. Specifically, by increasing the sample carrier 100 (hardware) and the automatic program (software), rapid sample testing is realized, the accuracy of sample testing is improved, and the efficiency of sample testing is improved. By monitoring and recording the roughness data of the sample, the state of the probe is monitored, and the accuracy of the test is guaranteed by automatically replacing the probe, which improves the accuracy of the test and improves the test efficiency.

[0069] The embodiment of the present application also provides a silicon wafer test system, which comprises a sample carrier 100, a sample carrier 200 and a control module, and the control module is used to execute any one of the above methods.

[0070] In some embodiments, the height of the sample carrier 100 can match the height of the sample carrier 200. As an example, the height of the sample carrier 100 is the same as the height of the sample carrier 200. As another example, the absolute value of the difference between the height of the sample carrier 100 and the height of the sample carrier 200 is less than a target difference value. As yet another example, the ratio of the absolute value of the difference between the height of the sample carrier 100 and the height of the sample carrier 200 to the height of the sample carrier 200 is less than a target ratio value. The target difference value and the target ratio value can be selected according to the actual application or pre-set, and the above embodiment does not limit this.

[0071] It should be noted that each embodiment in the present application is described in a progressive manner, and the same or similar parts of each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, for product embodiments, since they are basically similar to method embodiments, they are described more simply, and the relevant parts can be referred to the part of the method embodiment.

[0072] Unless otherwise defined, technical terms or scientific terms used in the present disclosure shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first", "second", and the like, as used in the present disclosure, do not imply any order, quantity, or importance, but are used to distinguish different components. The terms "include", "comprise", and the like, mean to encompass the elements listed after such terms and equivalents thereof, and do not exclude other elements. The terms "connected", "coupled", and the like, do not necessarily mean physically or mechanically connected, but can include electrical connection, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like, are used only to indicate relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0073] It can be understood that when an element such as a layer, a film, a region, or a substrate is referred to as being "on" or "under" another element, it can be "directly" on or under the other element, or an intervening element can also be present.

[0074] In the description of the above-described embodiments, specific features, structures, materials, or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The above description is merely illustrative of the disclosure and does not limit the scope of the disclosure. Any modifications made within the scope of the disclosure disclosed herein should be encompassed by the scope of the disclosure. Therefore, the scope of the disclosure should be based on the scope of the claims.

Claims

1. A silicon wafer testing method, characterized in that, The method for testing the roughness of silicon wafers includes: Perform standard sample testing to obtain standard sample test data; the standard sample testing is performed on a standard sample stage; If the standard test data indicates that the probe needs to be replaced, repeat the steps of replacing the probe and performing the standard test until the latest standard test data indicates that the probe does not need to be replaced. If the standard test data indicates that the probe does not need to be replaced, a sample test is performed to obtain sample test data; the sample test is performed on a sample stage; if the sample test is not completed, it is determined whether a standard test needs to be performed again; if a standard test needs to be performed again, the standard test is performed again. Wherein, the size of the standard sample is smaller than the size of the sample, the size of the standard sample stage is smaller than the size of the sample stage, and the heights of the standard sample stage and the sample stage are matched; the standard sample test is a standard sample roughness test, the sample test is a sample roughness test, and the scanning parameters corresponding to the standard sample test and the sample test are consistent; The process of determining whether a probe needs to be replaced using the standard test data includes: if the standard test data is within the target value range, it is determined that the standard test data indicates that the probe does not need to be replaced; or, if the standard test data is not within the target value range, it is determined that the standard test data indicates that the probe needs to be replaced.

2. The silicon wafer testing method according to claim 1, characterized in that, The method further includes: If it is not necessary to perform standard sample testing again, continue with sample testing.

3. The silicon wafer testing method according to claim 1, characterized in that, The method further includes: Once the sample testing is complete, the test is terminated.

4. The silicon wafer testing method according to claim 1, characterized in that, The method further includes: Set the corresponding test points and / or scanning parameters for the standard sample test; and / or, Set the corresponding test points and / or scanning parameters for sample testing.

5. The silicon wafer testing method according to claim 4, characterized in that, The scanning parameters include one or more of the following: test area, scanning rate, and scanning resolution.

6. A silicon wafer testing system, characterized in that, The system includes: Standard sample stage; Sample stage; A control module for performing the method according to any one of claims 1 to 5.

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