Overlay measurement method, device, equipment and storage medium

Abstract

The present application discloses an overlay measurement method, device, equipment and storage medium, and relates to the field of photolithography technology. The present application is applied to a controller of an imaging overlay measurement device, which responds to a test instruction for a wafer to be tested, moves the aperture to multiple test positions, and measures the error introduced by the device at each test position; determines the target aperture position corresponding to the wafer to be tested when the device error is minimized based on the impact of the change in the test position on the device error; adjusts the aperture to the target aperture position, and controls the imaging overlay measurement device to perform overlay measurement on the overlay mark in the wafer to be tested. The present application performs overlay measurement on the wafer to be tested when the error introduced by the aperture is minimized, thereby improving the accuracy of the overlay measurement.

Description

Technical Field

[0001] The present application relates to the field of photolithography technology, and more specifically, to an overlay measurement method, device, equipment and storage medium. Background Art

[0002] In the photolithography process, overlay error is an important parameter to measure overlay accuracy, which can be measured by imaging overlay measurement equipment. The measurement method of imaging overlay measurement equipment is: using apertures of different apertures to illuminate the overlay mark or overlay mark on the wafer, measuring the overlay mark on the wafer, and determining the overlay error based on the alignment error between the overlay mark of the current photolithography layer and the previous photolithography layer. Among them, the position and angle of the aperture can control the propagation direction and incident range of the light, thereby ensuring that the illumination of the measurement area is uniform and of sufficient intensity, which is conducive to the imaging system capturing a clear image of the overlay mark and improving the accuracy of the measurement.

[0003] In order to ensure the accuracy of imaging overlay measurement, it is necessary to pre-calibrate the position of each aperture to ensure that the center of the aperture is located at the center of the illumination light path and is in the optimal measurement state. For example, during the equipment integration and adjustment stage, the position of each aperture is calibrated offline using optical methods. However, due to factors such as optomechanical drift and process differences in measuring wafers, the pre-calibrated aperture position may not guarantee that the center of the aperture is always located at the center of the illumination light path, and the optimal aperture position may be different for different measurement objects. Therefore, the aperture position calibrated by integrated adjustment may not be suitable for all measurement objects, resulting in reduced accuracy of overlay measurement.

[0004] Based on this, there is an urgent need for a method to locate the optimal measurement position of the aperture so that the imaging overlay measurement device can reach the optimal measurement state during each measurement and improve the accuracy of the overlay measurement. Summary of the invention

[0005] In view of the above problems, the present application provides an overlay measurement method, device, equipment and storage medium to achieve the purpose of positioning the best measurement position of the aperture and improving the overlay measurement accuracy of the imaging overlay measurement device. The specific scheme is as follows:

[0006] In a first aspect, the present application provides an overlay measurement method, which is applied to a controller of an imaging overlay measurement device, wherein the imaging overlay measurement device includes at least one aperture, and the overlay measurement method includes:

[0007] In response to the test instruction, obtaining a preset number of test positions corresponding to an aperture in the at least one aperture;

[0008] Control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and obtain the device error of the imaging overlay measurement device at each of the test positions, wherein the device error represents the error introduced by the change of the aperture position;

[0009] Determining a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error;

[0010] The aperture is adjusted to the target aperture position, and the imaging overlay measurement device is controlled to perform overlay measurement on the overlay mark in the wafer to be measured.

[0011] In a possible implementation, determining the target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error includes:

[0012] Fitting each of the test positions and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents a functional relationship between the test position and the device error corresponding to the wafer to be tested;

[0013] The test position corresponding to when the objective function is at a minimum value is determined as the target aperture position corresponding to the wafer to be tested.

[0014] In a possible implementation, controlling the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and obtaining the device error of the imaging overlay measurement device at each of the test positions, respectively, includes:

[0015] Control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be tested, and obtain the overlay error corresponding to each of the test positions, wherein the overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angles are 0° and 180°;

[0016] According to the overlay error corresponding to each of the test positions, the device error corresponding to each of the test positions is determined.

[0017] In a possible implementation, determining the device error corresponding to each of the test positions according to the overlay error corresponding to each of the test positions includes:

[0018] From the overlay error corresponding to the test position, obtain a first offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 0°, and a second offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 180°;

[0019] Determine an initial device error corresponding to the overlay mark to be measured at the test position according to a difference between the first offset and the second offset corresponding to the overlay mark to be measured;

[0020] The average value of the initial device errors corresponding to each of the overlay marks to be measured at the test position is determined as the device error corresponding to the test position.

[0021] In a possible implementation, obtaining a preset number of test positions corresponding to an aperture of the at least one aperture includes:

[0022] Acquiring a pre-calibrated initial position corresponding to an aperture of the at least one aperture;

[0023] The initial position is adjusted according to a preset step distance to obtain a preset number of test positions.

[0024] A second aspect of the present application provides an overlay measurement device, which is applied to a controller of an imaging overlay measurement device, wherein the imaging overlay measurement device includes at least one aperture, and the overlay measurement device includes:

[0025] A test position acquisition unit, configured to acquire a preset number of test positions corresponding to an aperture in the at least one aperture in response to a test instruction;

[0026] An error acquisition unit, used for controlling the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and respectively acquiring a device error of the imaging overlay measurement device at each of the test positions, wherein the device error represents an error introduced by the change in the aperture position;

[0027] A target position determination unit, used to determine a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error;

[0028] The control measurement unit is used to adjust the aperture to the target aperture position and control the imaging overlay measurement device to perform overlay measurement on the overlay mark in the wafer to be measured.

[0029] In a possible implementation, the target position determination unit includes:

[0030] A data fitting subunit is used to fit each of the test positions and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents a functional relationship between the test position and the device error corresponding to the wafer to be tested;

[0031] The target position determination subunit is used to determine the test position corresponding to the minimum value of the objective function as the target aperture position corresponding to the wafer to be tested.

[0032] In a possible implementation, the error acquisition unit includes:

[0033] An overlay error acquisition subunit is used to control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be tested, and respectively obtain the overlay error corresponding to each of the test positions, wherein the overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angle is 0° and 180°;

[0034] The device error determination subunit is used to determine the device error corresponding to each of the test positions according to the overlay error corresponding to each of the test positions.

[0035] In a third aspect, the present application provides an overlay measurement device, comprising at least one processor and a memory connected to the processor, wherein:

[0036] The memory is used to store computer programs;

[0037] The processor is used to execute the computer program so that the overlay measurement device can implement any one of the overlay measurement methods.

[0038] A fourth aspect of the present application provides a computer storage medium, which carries one or more computer programs. When the one or more computer programs are executed by an overlay measurement device, the overlay measurement device can implement any one of the overlay measurement methods.

[0039] It can be seen from the above technical solution that the overlay measurement method provided by the embodiment of the present application moves the aperture to multiple test positions in response to the test instruction of the wafer to be tested, and measures the error introduced by the device at each test position. Since only the position of the aperture changes in the imaging overlay measurement device, the error introduced by the device is assumed to be the error introduced by the change of the aperture position. Based on the influence of the change of the aperture position on the device error, the aperture position with the minimum device error is determined as the target position corresponding to the wafer to be tested.

[0040] Position the aperture of the imaging overlay measurement device to the target position, and perform overlay measurement on the wafer to be measured when the error introduced by the aperture is minimized, thereby improving the accuracy of the overlay measurement. Moreover, compared with the prior art, the present application adjusts the aperture position according to the measurement result of the wafer to be measured, so that the target aperture position is more suitable for the wafer to be measured. Based on this, if the wafer measured by the imaging overlay measurement device is replaced, the present application can personalize the optimal aperture position for the wafer, thereby improving the flexibility of the imaging overlay measurement device. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0042] Figure 1 A schematic diagram of an aperture provided in an embodiment of the present application;

[0043] Figure 2 A schematic diagram of a flow chart of a method for implementing overlay measurement provided in an embodiment of the present application;

[0044] Figure 3 A schematic diagram of a process for controlling the aperture position for overlay measurement provided in an embodiment of the present application;

[0045] Figure 4 A schematic diagram of the structure of an overlay measurement device provided in an embodiment of the present application;

[0046] Figure 5 A schematic diagram of the structure of an overlay measurement device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] Usually, in order to adapt to different lighting environments or imaging requirements, imaging overlay measurement equipment is generally equipped with different specifications of illumination aperture diaphragms. Figure 1 , the aperture diagram provided in the embodiment of the present application is usually an illumination aperture aperture of three specifications: large, medium, and small. In the overlay measurement process, aperture apertures of different specifications are switched according to demand, and the aperture aperture is moved to the corresponding calibration position. However, in the process of switching and moving the aperture, due to the optical-mechanical drift caused by mechanical structure displacement, temperature change, air disturbance, etc., the overlay measurement device for imaging the aperture at the calibration position may not always guarantee the optimal measurement performance. And because the optimal illumination aperture aperture positions corresponding to different wafers to be measured are different, and the calibration position is not the optimal position of the current wafer to be measured, the overlay measurement device for imaging the aperture at the calibration position cannot achieve the optimal measurement state for the wafer to be measured, resulting in low accuracy of the measurement result.

[0049] To solve the above technical problems, an embodiment of the present application provides an overlay measurement method, which is applied to a controller of an imaging overlay measurement device, and the controller can control each aperture in the mobile imaging overlay measurement device, wherein the imaging overlay measurement device is configured with at least one aperture to meet different measurement requirements.

[0050] Reference Figure 2 , a flow chart of a method for implementing an overlay measurement provided in an embodiment of the present application is provided, and an overlay measurement method applied to a controller is described. Specifically, the flow chart includes the following steps:

[0051] Step S110, in response to the test instruction, obtaining a preset number of test positions corresponding to an aperture in at least one aperture.

[0052] It is understandable that although the imaging overlay measurement device is configured with multiple apertures, only one aperture is required for actual measurement. Therefore, in response to the measurement instruction, a target aperture that adapts to the current lighting environment and meets the measurement requirements is determined from the multiple apertures. In the embodiment of the present application, steps S110-S140 are all adjustments to the target aperture.

[0053] The embodiment of the present application finds the position of the diaphragm in the best measurement state, determines multiple test positions for diaphragm calibration, adjusts the diaphragm between the multiple test positions, and observes the measurement effect of the imaging overlay measurement device of the diaphragm at different test positions, so as to determine a position with the best test effect or measurement state from among the numerous test positions.

[0054] Optionally, obtaining a preset number of test positions corresponding to the aperture includes: obtaining a pre-calibrated initial position corresponding to the aperture; and adjusting the initial position according to a preset step distance to obtain a preset number of test positions.

[0055] Reference Figure 1 , which includes three aperture diaphragms of different specifications. The planes where the X and Y planes are located are the planes where the aperture diaphragms are located, and the Z direction is the light transmission direction, that is, the direction of the optical axis. During the optical integration and adjustment stage of the imaging overlay equipment, the initial position of each aperture diaphragm will be calibrated. For example: the initial position of the large aperture diaphragm (X0 Large , Y0 Large ), the initial position of the middle aperture diaphragm (X0 Middle , Y0 Middle ), the initial position of the small aperture diaphragm (X0 Small , Y0 Small ).

[0056] In the embodiment of the present application, a small aperture diaphragm is used as the target diaphragm, and multiple test positions are determined according to the initial position of the small aperture diaphragm according to the preset step distance, wherein the number of test positions can be set according to the requirement for the accuracy of the diaphragm position adjustment. If it is necessary to locate the best diaphragm position with high accuracy, as many test positions as possible can be determined. Conversely, if the positioning accuracy of the best diaphragm position is not required, the number of test positions can be reduced. The setting of the step distance is similar. If the preset number is large, the step distance can be reduced to avoid the test position after multiple adjustments exceeding the adjustable position range of the diaphragm.

[0057] Based on this, referring to the following formula (1), the coordinates of each test position are determined based on the initial position.

[0058] (1)

[0059] Among them, (X Start ,Y Start )、(X end ,Y end ) represent the starting coordinates and the ending coordinates of the test position respectively; nx and ny represent the number of unidirectional test positions of the small aperture diaphragm in the X and Y directions respectively, which is 1 / 2 of the total number of test positions; Stepx and Stepy represent the stepping distances of the small aperture diaphragm in the X and Y directions respectively. It can be understood that the coordinates of the test position between the starting coordinates and the ending coordinates can be obtained by changing the value of n in formula (1), but the replaced value is a positive integer not exceeding n.

[0060] Based on this, a plurality of test positions of the aperture to be adjusted can be obtained.

[0061] Step S120 , controlling the aperture to move to each test position in sequence to perform overlay measurement on the wafer to be tested, and obtaining the device error of the imaging overlay measurement device at each test position.

[0062] Based on the multiple test positions of the aperture obtained in step S110, the aperture is adjusted to move to each test position, and the imaging overlay measurement device is controlled to perform overlay measurement on the wafer to be tested at each test position. Specifically, the test positions of the aperture can be adjusted in sequence according to the positional relationship between the test position and the initial position, or the coordinate sequence from the starting coordinate to the end coordinate determined in step S110, so as to achieve the purpose of not missing any test position.

[0063] The embodiment of the present application evaluates the measurement state of the device based on the error introduced by the imaging overlay measurement device at each test position. Since only the aperture position changes in the imaging overlay measurement device, the error introduced by the device can be understood as the error caused by the change in the aperture position.

[0064] It is understandable that if the error introduced by the imaging overlay test equipment is to be tested, it is necessary to compare the overlay measurement results of the wafer to be tested at 0° and 180°. In theory, the overlay measurement results of the wafer to be tested at 0° and 180° should be consistent, or the deviation between the overlay measurement results of the wafer to be tested at 0° and 180° should not exceed a certain threshold, and the deviation exceeding the threshold can be understood as the error introduced by the equipment.

[0065] Based on this, the embodiment of the present application not only controls the measurement of the overlay measurement results corresponding to each test position, but also needs to control the measurement of the overlay measurement results corresponding to 0° and 180° of the wafer to be tested at each test position.

[0066] In a possible implementation, the aperture is controlled to move to each test position in turn to perform overlay measurement on the wafer to be tested, and the overlay error corresponding to each test position is obtained respectively. The overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angles are 0° and 180° respectively; based on the overlay error corresponding to each test position, the equipment error corresponding to each test position is determined.

[0067] Specifically, refer to Figure 3 , the embodiment of the present application provides a flow chart of controlling the aperture position for overlay measurement, which explains the process of controlling the aperture movement for overlay measurement. First, move the aperture to the initial position, and use the initial position as the starting point to perform overlay measurement on the wafers to be tested at 0° and 180°, respectively, to obtain overlay data or overlay values, i.e., overlay measurement results. After completing the measurement of the initial position, determine whether all test positions have been measured. If the judgment result is no, move the aperture to the next test position, and perform overlay measurement on the wafers to be tested at 0° and 180°, respectively. Based on this, stop moving the aperture until all test positions have been measured, and determine the device error corresponding to each test position based on all the overlay measurement results obtained.

[0068] Furthermore, based on the overlay error corresponding to each test position, the equipment error corresponding to each test position is determined, including: obtaining, from the overlay error corresponding to the test position, a first offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 0°, and a second offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 180°; based on the difference between the first offset and the second offset corresponding to the overlay mark to be measured, determining the initial equipment error corresponding to the overlay mark to be measured at the test position; and determining the average value of the initial equipment error corresponding to each overlay mark to be measured at the test position as the equipment error corresponding to the test position.

[0069] It is understandable that the overlay value obtained by the imaging overlay measurement equipment for the wafer to be tested is the overlay accuracy (Overlay, OVL), that is, the overlay offset between two different layers on the wafer. Based on this, from the overlay measurement results corresponding to each test position, the first offset of 0° and the second offset of 180° measured at the test position of the wafer to be tested are obtained. It is understandable that the wafer to be tested usually contains multiple overlay marks. When performing overlay measurement, each overlay mark is overlaid. The obtained overlay measurement result contains the overlay value corresponding to each overlay mark. Therefore, the first offset of 0° and the second offset of 180° corresponding to each overlay mark at the test position can be obtained from the overlay measurement results corresponding to a test position.

[0070] Further, according to the first offset of 0° and the second offset of 180° of each overlay mark of the wafer to be measured at each test position, the initial device error corresponding to each overlay mark to be measured at the test position is determined. Specifically, refer to the following formula (2).

[0071] (2)

[0072] Among them, (x i ,y i ) represents the coordinates of the test position, k represents the kth overlay mark among all the overlay marks on the wafer to be tested; Indicates that (x i ,y i ) The initial device error corresponding to the kth overlay mark at the test position; Indicates that (x i ,y i ) the first offset of 0° of the kth overlay mark at the test position; Indicates that (x i ,y i ) is the second offset of 180° of the kth overlay mark at the test position. It can be understood that the offset in the embodiment of the present application is a vector, that is, the signs of the OVL true values ​​at 0° and 180° are opposite, the equipment error TIS will not change, and the addition of the two can achieve the effect of making a difference in the offset. Therefore, the first offset OVL_0 of a certain overlay mark at 0°=OVL true value+TIS, and the second offset OVL_180 of the overlay mark at 180°=-OVL true value+TIS. Based on this, and The result of the addition is twice the equipment error TIS.

[0073] Further, referring to the following formula (3), the average of the initial device errors corresponding to all the overlay marks at the test position is used as the device error introduced by the change of the aperture position at the test position.

[0074] (3)

[0075] Where n is the total number of overlay marks on the wafer to be tested, TIS_M xi,yi It means (x i ,y i )The device error corresponding to the test position.

[0076] Step S130 , determining a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error.

[0077] Step S140, adjusting the aperture to a target aperture position, and controlling an imaging overlay measurement device to perform overlay measurement on the overlay mark in the wafer to be measured.

[0078] It can be understood that the embodiment of the present application uses device error to quantify the measurement state of the imaging overlay measurement device. The larger the device error, the worse the device measurement state at the current test position. Based on this, the device errors corresponding to all test positions are counted, and the impact of the change in the test position on the device error is summarized. For example, the smaller the device error corresponding to the test position farther away from the initial position, it can be determined that the farther the aperture is from the initial position, the better the corresponding device measurement state. Based on this, within the range of the aperture allowed to move, the test position with the smallest device error is determined as the target aperture position for measuring the wafer to be measured.

[0079] In one possible implementation, the target aperture position corresponding to the wafer to be tested is determined based on the impact of the change in the test position on the device error, including: fitting each test position and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, the target function characterizing the functional relationship between the test position and the device error corresponding to the wafer to be tested; and determining the test position corresponding to the minimum value of the target function as the target aperture position corresponding to the wafer to be tested.

[0080] For all the above test positions (x i ,y i ), and the equipment error TIS_M corresponding to each test position xi,yi Data fitting is performed to obtain a function expression that can characterize the influence relationship between the test position and the equipment error, namely the objective function, as shown in the following formula (4).

[0081] (4)

[0082] Optionally, the objective function is fitted into a binary quadratic function, as shown in (5), so as to determine the minimum value of the device error from the objective function, thereby determining the test position corresponding to the aperture when the imaging overlay measurement device is in the optimal measurement state as the target aperture position.

[0083] (5)

[0084] Among them, K 0 , K 1 , K 2 , K 3 , K 4 , K 5 Represent each coefficient respectively, and the specific value of the coefficient can be determined according to the data fitting results.

[0085] Furthermore, based on the objective function of formula (5), we can solve TIS_M xi,yi The test position corresponding to the minimum value (x i ,y i ), the test position is the target aperture position. When the aperture is at this position, the imaging overlay measurement device has the best measurement state. The aperture is controlled to move to the target aperture position, and at this time, the imaging overlay measurement device formally performs overlay measurement on the wafer to be measured.

[0086] In summary, the overlay measurement method provided in the embodiment of the present application moves the aperture to multiple test positions in response to the test instruction of the wafer to be tested, and measures the error introduced by the device at each test position. Since only the position of the aperture changes in the imaging overlay measurement device, the error introduced by the device is assumed to be the error introduced by the change in the aperture position. Based on the influence of the change in the aperture position on the device error, the aperture position with the minimum device error is determined as the target position corresponding to the wafer to be tested.

[0087] Position the aperture of the imaging overlay measurement device to the target position, and perform overlay measurement on the wafer to be measured when the error introduced by the aperture is minimized, thereby improving the accuracy of the overlay measurement. Moreover, compared with the prior art, the present application adjusts the aperture position according to the measurement result of the wafer to be measured, so that the target aperture position is more suitable for the wafer to be measured. Based on this, if the wafer measured by the imaging overlay measurement device is replaced, the present application can personalize the optimal aperture position for the wafer, thereby improving the flexibility of the imaging overlay measurement device.

[0088] The following is a description of the overlay measurement device provided in an embodiment of the present application. The overlay measurement device described below and the overlay measurement method described above can be referenced to each other.

[0089] First, combine Figure 4 , an overlay measurement device for a controller used in an imaging overlay measurement device is introduced, such as Figure 4 As shown, the overlay measurement device may include:

[0090] The test position acquisition unit 100 is used to acquire a preset number of test positions corresponding to an aperture in the at least one aperture in response to a test instruction;

[0091] An error acquisition unit 200 is used to control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and to respectively acquire the device error of the imaging overlay measurement device at each of the test positions, wherein the device error represents the error introduced by the change in the aperture position;

[0092] A target position determination unit 300, configured to determine a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error;

[0093] The control and measurement unit 400 is used to adjust the aperture to the target aperture position, and control the imaging overlay measurement device to perform overlay measurement on the overlay mark in the wafer to be measured.

[0094] In a possible implementation, the target position determination unit 300 includes:

[0095] A data fitting subunit is used to fit each of the test positions and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents a functional relationship between the test position and the device error corresponding to the wafer to be tested;

[0096] The target position determination subunit is used to determine the test position corresponding to the minimum value of the objective function as the target aperture position corresponding to the wafer to be tested.

[0097] In a possible implementation, the error acquisition unit 200 includes:

[0098] An overlay error acquisition subunit is used to control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be tested, and respectively obtain the overlay error corresponding to each of the test positions, wherein the overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angle is 0° and 180°;

[0099] The device error determination subunit is used to determine the device error corresponding to each of the test positions according to the overlay error corresponding to each of the test positions.

[0100] In a possible implementation, the device error determination subunit includes:

[0101] An offset acquisition subunit is used to obtain, from the overlay error corresponding to the test position, a first offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 0°, and a second offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 180°;

[0102] an initial device error determination subunit, configured to determine an initial device error corresponding to the overlay mark to be measured at the test position according to a difference between the first offset and the second offset corresponding to the overlay mark to be measured;

[0103] The device error determination subunit is used to determine the average value of the initial device errors corresponding to each of the overlay marks to be measured at the test position as the device error corresponding to the test position.

[0104] In a possible implementation, the test position acquisition unit 100 includes:

[0105] An initial position acquisition subunit, used to acquire a pre-calibrated initial position corresponding to the aperture;

[0106] The position adjustment subunit is used to adjust the initial position according to a preset step distance to obtain a preset number of test positions.

[0107] In summary, in response to the test instruction for the wafer to be tested, the embodiment of the present application moves the aperture to multiple test positions, and measures the error introduced by the device at each test position. Since only the position of the aperture changes in the imaging overlay measurement device, the error introduced by the device is assumed to be the error introduced by the change in the aperture position. Based on the influence of the change in the aperture position on the device error, the aperture position with the minimum device error is determined as the target position corresponding to the wafer to be tested.

[0108] Position the aperture of the imaging overlay measurement device to the target position, and perform overlay measurement on the wafer to be measured when the error introduced by the aperture is minimized, thereby improving the accuracy of the overlay measurement. Moreover, compared with the prior art, the present application adjusts the aperture position according to the measurement result of the wafer to be measured, so that the target aperture position is more suitable for the wafer to be measured. Based on this, if the wafer measured by the imaging overlay measurement device is replaced, the present application can personalize the optimal aperture position for the wafer, thereby improving the flexibility of the imaging overlay measurement device.

[0109] The overlay measurement device provided in the embodiment of the present application can be applied to overlay measurement equipment.

[0110] Figure 5 The schematic diagram of the structure of the overlay measurement device is shown. Figure 5The structure of the overlay measurement device may include: at least one processor 10, at least one memory 20, at least one communication bus 30 and at least one communication interface 40.

[0111] In the embodiment of the present application, the number of the processor 10 , the memory 20 , the communication bus 30 , and the communication interface 40 is at least one, and the processor 10 , the memory 20 , and the communication interface 40 communicate with each other through the communication bus 30 .

[0112] The processor 10 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present invention.

[0113] The memory 20 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), etc., such as at least one disk memory.

[0114] The memory stores a program, and the processor can call the program stored in the memory, and the program is used to implement each processing flow in the aforementioned overlay measurement method.

[0115] An embodiment of the present application also provides a computer storage medium, which can store a program suitable for execution by a processor, and the program is used to implement each processing flow in the aforementioned overlay measurement method.

[0116] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0117] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0118] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An overlay measurement method, characterized in that: A controller applied to an imaging overlay measurement device, wherein the imaging overlay measurement device comprises at least one aperture, and the overlay measurement method comprises: In response to the test instruction, obtaining a preset number of test positions corresponding to an aperture in the at least one aperture; Control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and obtain the device error of the imaging overlay measurement device at each of the test positions, wherein the device error represents the error introduced by the change of the aperture position; Determining a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error; The aperture is adjusted to the target aperture position, and the imaging overlay measurement device is controlled to perform overlay measurement on the overlay mark in the wafer to be measured.

2. The overlay measurement method according to claim 1, characterized in that: Determining the target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error includes: Fitting each of the test positions and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents a functional relationship between the test position and the device error corresponding to the wafer to be tested; The test position corresponding to when the objective function is at a minimum value is determined as the target aperture position corresponding to the wafer to be tested.

3. The overlay measurement method according to claim 1, characterized in that: The step of controlling the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and obtaining the device error of the imaging overlay measurement device at each of the test positions, respectively, comprises: Control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be tested, and obtain the overlay error corresponding to each of the test positions, wherein the overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angles are 0° and 180°; According to the overlay error corresponding to each of the test positions, the device error corresponding to each of the test positions is determined.

4. The overlay measurement method according to claim 3, characterized in that: Determining the device error corresponding to each of the test positions according to the overlay error corresponding to each of the test positions includes: From the overlay error corresponding to the test position, obtain a first offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 0°, and a second offset corresponding to each overlay mark to be measured in the wafer to be tested when the rotation angle of the wafer to be tested is 180°; Determine an initial device error corresponding to the overlay mark to be measured at the test position according to a difference between the first offset and the second offset corresponding to the overlay mark to be measured; The average value of the initial device errors corresponding to each of the overlay marks to be measured at the test position is determined as the device error corresponding to the test position.

5. The overlay measurement method according to claim 1, characterized in that: The obtaining of a preset number of test positions corresponding to an aperture of the at least one aperture comprises: Acquiring a pre-calibrated initial position corresponding to an aperture of the at least one aperture; The initial position is adjusted according to a preset step distance to obtain a preset number of test positions.

6. An overlay measurement device, characterized in that: A controller applied to an imaging overlay measurement device, wherein the imaging overlay measurement device comprises at least one aperture, and the overlay measurement device comprises: A test position acquisition unit, configured to acquire a preset number of test positions corresponding to an aperture in the at least one aperture in response to a test instruction; An error acquisition unit, used for controlling the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be measured, and respectively acquiring a device error of the imaging overlay measurement device at each of the test positions, wherein the device error represents an error introduced by the change in the aperture position; A target position determination unit, used to determine a target aperture position corresponding to the wafer to be tested according to the influence of the change of the test position on the device error; The control measurement unit is used to adjust the aperture to the target aperture position and control the imaging overlay measurement device to perform overlay measurement on the overlay mark in the wafer to be measured.

7. The overlay measurement device according to claim 6, characterized in that: The target position determination unit comprises: A data fitting subunit is used to fit each of the test positions and the device error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents a functional relationship between the test position and the device error corresponding to the wafer to be tested; The target position determination subunit is used to determine the test position corresponding to the minimum value of the objective function as the target aperture position corresponding to the wafer to be tested.

8. The overlay measurement device according to claim 6, characterized in that: The error acquisition unit comprises: An overlay error acquisition subunit is used to control the aperture to move to each of the test positions in sequence to perform overlay measurement on the wafer to be tested, and respectively obtain the overlay error corresponding to each of the test positions, wherein the overlay error includes: the overlay mark offset data corresponding to the wafer to be tested when the rotation angle is 0° and 180°; The device error determination subunit is used to determine the device error corresponding to each of the test positions according to the overlay error corresponding to each of the test positions.

9. An overlay measurement device, characterized in that: The method comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs; The processor is used to execute the computer program so that the overlay measurement device can implement the overlay measurement method according to any one of claims 1 to 5.

10. A computer storage medium, characterized in that: The storage medium carries one or more computer programs, and when the one or more computer programs are executed by the overlay measurement device, the overlay measurement device can implement the overlay measurement method as described in any one of claims 1 to 5.

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