CN119376194B - Overlay measurement method, device, equipment and storage medium - Google Patents
Overlay measurement method, device, equipment and storage medium Download PDFInfo
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- CN119376194B CN119376194B CN202411931229.7A CN202411931229A CN119376194B CN 119376194 B CN119376194 B CN 119376194B CN 202411931229 A CN202411931229 A CN 202411931229A CN 119376194 B CN119376194 B CN 119376194B
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70605—Workpiece metrology
- G03F7/70616—Monitoring the printed patterns
- G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70605—Workpiece metrology
- G03F7/706843—Metrology apparatus
- G03F7/706845—Calibration, e.g. tool-to-tool calibration, beam alignment, spot position or focus
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- Length Measuring Devices By Optical Means (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
Abstract
The application discloses an overlay measurement method, an overlay measurement device, overlay measurement equipment and a storage medium, and relates to the technical field of lithography. The method is applied to a controller of imaging overlay measurement equipment, responds to a test instruction of a wafer to be tested, moves a diaphragm to a plurality of test positions, measures errors introduced by the equipment at each test position, determines a target diaphragm position corresponding to the wafer to be tested under the condition that the equipment errors are minimum according to the influence of the change of the test positions on the equipment errors, adjusts the diaphragm to the target diaphragm position, controls the imaging overlay measurement equipment, and performs overlay measurement on overlay marks in the wafer to be tested. Under the condition that the error introduced by the diaphragm is minimum, the overlay measurement is carried out on the wafer to be measured, and the accuracy of the overlay measurement is improved.
Description
Technical Field
The present application relates to the field of photolithography, and in particular, to an overlay measurement method, apparatus, device, and storage medium.
Background
In the photolithography process, the overlay error is an important parameter for measuring the overlay accuracy, and can be measured by an imaging overlay measurement device. The imaging overlay measurement device adopts a measurement mode that the overlay mark or the overlay mark on the wafer is illuminated by diaphragms with different apertures, the overlay mark on the wafer is measured, and the overlay error is determined based on the alignment error of the overlay mark of the current photoetching layer and the last photoetching layer. The position and the angle of the diaphragm can control the propagation direction and the incidence range of light, so that the illumination of a measurement area is ensured to be uniform and strong enough, the imaging system is facilitated to capture a clear overlay mark image, and the measurement accuracy is improved.
In order to ensure the accuracy of imaging overlay measurement, the center of each diaphragm is ensured to be positioned at the center of an illumination light path and in an optimal measurement state by calibrating the position mode of each diaphragm in advance. For example, in the device integration adjustment stage, the position of each diaphragm is calibrated offline using optical methods. However, due to factors such as optical-mechanical drift and process variation of the measurement wafer, the pre-calibrated diaphragm position may not ensure that the center of the diaphragm is always located at the center position of the illumination light path, and the optimal diaphragm positions corresponding to different measurement objects may be different, so that the integrated adjustment calibrated diaphragm position is not necessarily suitable for all measurement objects, thereby reducing the accuracy of overlay measurement.
Based on the above, a method for positioning the optimal measurement position of the diaphragm is needed, so that the imaging overlay measurement device achieves an optimal measurement state during each measurement, and the overlay measurement accuracy is improved.
Disclosure of Invention
In view of the above problems, the present application provides an overlay measurement method, apparatus, device and storage medium, so as to achieve the purpose of locating an optimal measurement position of a diaphragm and improving overlay measurement accuracy of an imaging overlay measurement device. The specific scheme is as follows:
the first aspect of the present application provides an overlay measurement method, applied to a controller of an imaging overlay measurement apparatus, the imaging overlay measurement apparatus including at least one diaphragm, the overlay measurement method comprising:
Responding to a test instruction, and acquiring a preset number of test positions corresponding to one diaphragm in the at least one diaphragm;
The diaphragm is controlled to sequentially move to each test position to carry out overlay measurement on a wafer to be measured, and equipment errors of the imaging overlay measurement equipment at each test position are respectively obtained, wherein the equipment errors represent errors introduced by position changes of the diaphragm;
determining a target diaphragm position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error;
and adjusting the diaphragm to the target diaphragm position, controlling the imaging overlay measurement equipment, and performing overlay measurement on the overlay mark in the wafer to be measured.
In one possible implementation, the determining, according to the influence of the change of the test position on the equipment error, the target aperture position corresponding to the wafer to be tested includes:
Fitting each test position and the equipment error corresponding to the test position to obtain an objective function corresponding to the wafer to be tested, wherein the objective function represents a functional relationship between the test position and the equipment error corresponding to the wafer to be tested;
And determining the corresponding test position when the objective function is the minimum value as the corresponding target diaphragm position of the wafer to be tested.
In one possible implementation, the controlling the diaphragm to move to each test position in turn performs overlay measurement on a wafer to be tested, and respectively obtains an equipment error of the imaging overlay measurement equipment at each test position, including:
The diaphragm is controlled to sequentially move to each test position to carry out overlay measurement on the wafer to be tested, and overlay errors corresponding to each test position are respectively obtained, wherein the overlay errors comprise overlay mark offset data corresponding to the wafer to be tested when the rotation angle of the wafer to be tested is 0 DEG and 180 DEG;
And determining the equipment error corresponding to each test position according to the overlay error corresponding to each test position.
In one possible implementation, the determining, according to the overlay error corresponding to each test position, the device error corresponding to each test position includes:
Acquiring a first offset corresponding to each overlay mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 0 degrees and a second offset corresponding to each overlay mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 180 degrees from the overlay errors corresponding to the test positions;
Determining an initial equipment error corresponding to the overlay mark to be measured at the test position according to the difference value of the first offset and the second offset corresponding to the overlay mark to be measured;
And determining the average value of the initial equipment errors corresponding to each overlay mark to be measured at the test position as the equipment error corresponding to the test position.
In one possible implementation, the obtaining a preset number of test positions corresponding to one diaphragm in the at least one diaphragm includes:
Acquiring a pre-calibrated initial position corresponding to one diaphragm in the at least one diaphragm;
and adjusting the initial positions according to the preset stepping distance to obtain a preset number of test positions.
The second aspect of the present application provides an overlay measurement apparatus for use in a controller of an imaging overlay measurement device, the imaging overlay measurement device comprising at least one aperture, the overlay measurement apparatus comprising:
the test position acquisition unit is used for responding to the test instruction and acquiring a preset number of test positions corresponding to one diaphragm in the at least one diaphragm;
the error acquisition unit is used for controlling the diaphragm to sequentially move to each test position to carry out overlay measurement on a wafer to be measured, and respectively acquiring equipment errors of the imaging overlay measurement equipment at each test position, wherein the equipment errors represent errors introduced by the position change of the diaphragm;
The target position determining unit is used for determining a target diaphragm position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error;
And the control measurement unit is used for adjusting the diaphragm to the target diaphragm position, controlling the imaging overlay measurement equipment and performing overlay measurement on the overlay mark in the wafer to be measured.
In one possible implementation, the target position determining unit includes:
The data fitting subunit is used for fitting each test position and the equipment error corresponding to the test position to obtain an objective function corresponding to the wafer to be tested, wherein the objective function represents the functional relationship between the test position and the equipment error corresponding to the wafer to be tested;
and the target position determining subunit is used for determining the corresponding test position when the target function is the minimum value as the target diaphragm position corresponding to the wafer to be tested.
In one possible implementation, the error acquisition unit includes:
an overlay error acquisition subunit, configured to control the diaphragm to sequentially move to each test position to perform overlay measurement on a wafer to be tested, and respectively acquire an overlay error corresponding to each test position, where the overlay error includes overlay mark offset data corresponding to the wafer to be tested when a rotation angle is 0 ° and 180 °;
And the equipment error determining subunit is used for determining the equipment error corresponding to each test position according to the overlay error corresponding to each test position.
A third aspect of the application provides an overlay measurement apparatus comprising at least one processor and a memory coupled to the processor, wherein:
The memory is used for storing a computer program;
the processor is configured to execute the computer program to enable the overlay measurement apparatus to implement any one of the overlay measurement methods.
A fourth aspect of the present application provides a computer storage medium carrying one or more computer programs which, when executed by an overlay measurement apparatus, enable the overlay measurement apparatus to implement any one of the overlay measurement methods.
As can be seen from the above technical solution, in the overlay measurement method provided by the embodiment of the present application, in response to a test instruction of a wafer to be tested, the diaphragm is moved to a plurality of test positions, and the error introduced by the device at each test position is measured, and because the imaging overlay measurement device only has the position of the diaphragm changed, the error introduced by the device is defaulted to the error introduced by the change of the position of the diaphragm. And determining the diaphragm position with the minimum equipment error according to the influence of the change of the diaphragm position on the equipment error, and taking the diaphragm position as the target position corresponding to the wafer to be measured.
And positioning the diaphragm of the imaging overlay measurement device to a target position, and performing overlay measurement on the wafer to be measured under the condition that the error introduced by the diaphragm is minimum, so that the accuracy of the overlay measurement is improved. Compared with the prior art, the method and the device for adjusting the diaphragm position according to the measurement result of the wafer to be measured enable the target diaphragm position to be more suitable for the wafer to be measured, based on the method and the device, if the wafer measured by the imaging overlay measurement device is replaced, the optimal diaphragm position can be positioned for the wafer in a personalized mode, and flexibility of the imaging overlay measurement device is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present application, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of a diaphragm according to an embodiment of the present application;
Fig. 2 is a schematic flow chart of an overlay measurement method according to an embodiment of the present application;
FIG. 3 is a schematic flow chart of the overlay measurement for controlling the position of the diaphragm according to the embodiment of the present application;
Fig. 4 is a schematic structural diagram of an overlay measurement apparatus according to an embodiment of the present application;
fig. 5 is a schematic structural diagram of an overlay measurement apparatus according to an embodiment of the present application.
Detailed Description
The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
In order to adapt to different illumination environments or imaging requirements, the imaging overlay measurement device is generally configured with illumination aperture diaphragms with different specifications, and referring to fig. 1, a diaphragm schematic diagram provided in an embodiment of the present application is generally an illumination aperture diaphragm with three specifications, namely, a large, a medium and a small. In the process of overlay measurement, the aperture diaphragms with different specifications are switched according to requirements, and the aperture diaphragms are moved to corresponding calibration positions, however, in the process of switching the aperture diaphragms and moving the aperture diaphragms, the imaging overlay measurement equipment of the aperture diaphragms at the calibration positions may not always ensure the optimal measurement performance due to the optical mechanical drift generated by mechanical structural displacement, temperature change, air disturbance and the like. And because the positions of the optimal illumination aperture diaphragms corresponding to different wafers to be measured are different, and the calibration positions are not the optimal positions of the current wafers to be measured, the imaging overlay measurement equipment cannot reach the optimal measurement state of the wafers to be measured under the calibration positions of the diaphragms, and therefore the accuracy of measurement results is low.
In order to solve the technical problems, the embodiment of the application provides an overlay measurement method, which is applied to a controller of imaging overlay measurement equipment, wherein the controller can control each diaphragm in the imaging overlay measurement equipment to move, and the imaging overlay measurement equipment is provided with at least one diaphragm to meet different measurement requirements.
Referring to fig. 2, a schematic flow chart for implementing an overlay measurement method according to an embodiment of the present application is described for an overlay measurement method applied to a controller, and specifically, the flow chart includes the following steps:
Step S110, responding to the test instruction, and obtaining the preset number of test positions corresponding to one diaphragm in at least one diaphragm.
It can be understood that although the imaging overlay measurement device is configured with a plurality of diaphragms, only one diaphragm is needed in actual measurement, so that in response to a measurement instruction, a target diaphragm which is adapted to the current illumination environment and meets the measurement requirement is determined from the plurality of diaphragms, and in the embodiment of the application, all steps S110-S140 are the adjustment of the target diaphragm.
According to the embodiment of the application, the position of the best measurement state is searched for the diaphragm, a plurality of test positions are determined for diaphragm calibration, and the measuring effect of the imaging overlay measuring equipment of the diaphragm under different test positions is observed by adjusting the diaphragm among the plurality of test positions so as to determine one test effect or the position with the best measurement state from the plurality of test positions.
Optionally, acquiring the preset number of test positions corresponding to the diaphragms comprises acquiring the preset initial positions corresponding to the diaphragms, and adjusting the initial positions according to the preset stepping distance to obtain the preset number of test positions.
Referring to fig. 1, three aperture stops of different specifications are included, a plane in which the aperture stop X, Y is located is a plane in which the aperture stop is located, and a Z direction is a light passing direction, that is, an optical axis direction. In the optical integration adjustment stage of the imaging alignment device, the initial position of each aperture stop is calibrated, for example, the initial position (X0 Large,Y0Large) of a large aperture stop, the initial position (X0 Middle,Y0Middle) of a middle aperture stop and the initial position (X0 Small,Y0Small) of a small aperture stop.
According to the embodiment of the application, the small aperture diaphragm is used as the target diaphragm, a plurality of test positions are determined according to the initial position of the small aperture diaphragm and the preset stepping distance, wherein the number of the test positions can be set according to the requirement on the adjustment accuracy of the aperture position, if the best diaphragm position with high accuracy is required to be positioned, the number of the test positions can be determined as much as possible, otherwise, if the requirement on the positioning accuracy of the best diaphragm position is not high, the number of the test positions can be reduced adaptively. The setting of the stepping distance is the same, if the preset number is more, the stepping distance can be reduced in an adaptive manner, and the test position after multiple times of adjustment is prevented from exceeding the adjustable position range of the diaphragm.
Based on this, referring to the following equation (1), the coordinates of each test position are determined based on the initial position.
(1)
Wherein (X Start,YStart）、（Xend,Yend) respectively represents a starting point coordinate and an ending point coordinate of the test positions, nx and ny respectively represent the number of unidirectional test positions of the small aperture diaphragm at X, Y Fang Xina, which is 1/2 of the total number of the test positions, and Stepx and Stepy respectively represent the stepping distances of the small aperture diaphragm at X, Y. It will be appreciated that the coordinates of the test location between the start point coordinates and the end point coordinates can be obtained by changing the value of n in equation (1), but the value replaced is a positive integer not exceeding n.
Based on this, a plurality of test positions of the diaphragm to be adjusted can be obtained.
And step S120, the diaphragm is controlled to sequentially move to each test position to carry out overlay measurement on the wafer to be tested, and the equipment errors of the imaging overlay measurement equipment at each test position are respectively obtained.
Based on the plurality of test positions of the diaphragm obtained in the step S110, the diaphragm 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 measured at each test position. Specifically, the test positions of the diaphragms may be sequentially adjusted according to the positional relationship between the test positions and the initial positions, or the coordinate sequence from the start coordinates to the end coordinates determined in step S110, so as to achieve the purpose of not missing the test positions.
According to the embodiment of the application, the measurement state of the equipment is evaluated by the error introduced by the imaging overlay measurement equipment at each test position, and the error introduced by the equipment can be understood as the error caused by the change of the diaphragm position when only the diaphragm position in the imaging overlay measurement equipment is changed.
It will be appreciated that if the errors introduced by the imaging overlay test apparatus are to be tested, it is necessary to compare the overlay measurements of the wafer under test at 0 ° and 180 °, and theoretically the overlay measurements of the wafer under test at 0 ° and 180 ° should be consistent, or the deviation between the overlay measurements of the wafer under test at 0 ° and 180 ° should not exceed a certain threshold, and the deviation exceeding the threshold may be understood as the errors introduced by the apparatus.
Based on this, the embodiment of the application not only controls and measures the overlay measurement result corresponding to each test position, but also needs to control and measure the overlay measurement result corresponding to the wafer to be tested at 0 degrees and 180 degrees respectively at each test position.
In one possible implementation, the control diaphragm is sequentially moved to each test position to perform overlay measurement on the wafer to be tested, and the overlay errors corresponding to each test position are respectively obtained, wherein the overlay errors comprise overlay mark offset data corresponding to the wafer to be tested when the rotation angle is 0 DEG and 180 DEG, and equipment errors corresponding to each test position are determined according to the overlay errors corresponding to each test position.
Specifically, referring to fig. 3, a schematic flow chart of overlay measurement performed on a control diaphragm position according to an embodiment of the present application is described. Firstly, moving a diaphragm to an initial position, and respectively performing overlay measurement on a wafer to be measured at 0 DEG and 180 DEG by taking the initial position as a starting point to obtain overlay data or an overlay value, namely an overlay measurement result. After the initial position is measured, judging whether all the test positions are measured, if not, moving the diaphragm to the next test position, and performing overlay measurement on the wafers to be tested at 0 degrees and 180 degrees respectively. Based on the above, until all the test positions are also measured, stopping moving the diaphragm, and determining the equipment error corresponding to each test position based on all the obtained overlay measurement results.
Further, determining the equipment error corresponding to each test position according to the alignment error corresponding to each test position, wherein the equipment error comprises the steps of obtaining a first offset corresponding to each alignment mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 0 DEG and a second offset corresponding to each alignment mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 180 DEG from the alignment error corresponding to each test position, determining the initial equipment error corresponding to the alignment mark to be measured under the test position according to the difference value of the first offset and the second offset corresponding to the alignment mark to be measured, and determining the average value of the initial equipment error corresponding to each alignment mark to be measured under the test position as the equipment error corresponding to the test position.
It can be understood that the Overlay value measured by the imaging Overlay measurement device on the wafer to be measured is Overlay accuracy (OVL), i.e. the Overlay offset between two different layers on the wafer. Based on the above, a first offset of 0 degrees and a second offset of 180 degrees, which are measured at the test position, of the wafer to be tested are obtained from the overlay measurement results corresponding to each test position. It can be understood that the wafer to be measured generally includes a plurality of overlay marks, and when performing overlay measurement, the overlay measurement is performed on each overlay mark, and the obtained overlay measurement result includes an overlay value corresponding to each overlay mark. Thus, from the overlay measurement results corresponding to one test position, a first offset of 0 ° and a second offset of 180 ° for each overlay mark at that test position can be obtained.
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, determining an initial equipment error corresponding to each overlay mark to be measured at the test position, specifically, refer to the following formula (2).
(2)
Wherein, (x i,yi) represents the coordinate of the test position, and k represents the kth overlay mark in all overlay marks on the wafer to be tested; indicating an initial equipment error corresponding to the kth overlay mark at the (x i,yi) test position; A first offset of 0 ° representing the kth overlay mark at the (x i,yi) test position; A second offset of 180 deg. of the kth overlay mark at the (x i,yi) test position is represented. It can be understood that the offset of the embodiment of the present application is a vector, that is, the sign of OVL true values at 0 ° and 180 ° is opposite, the device error TIS is unchanged, and the addition of the two results in the offset difference. Thus, a first offset ovl_0=ovl true value+tis for a certain overlay mark at 0 °, and a second offset ovl_180= -OVL true value+tis for that overlay mark at 180 °. Based on this, the first and second light sources, And (3) withThe result of the addition is twice the device error TIS.
Further, referring to the following formula (3), taking the average value of the initial equipment errors corresponding to all the overlay marks at the test position as the equipment error introduced by the diaphragm position change under the characterization of the test position.
(3)
Where n is the total number of overlay marks on the wafer to be tested, TIS_M xi,yi represents the equipment error corresponding to the (x i,yi) test position.
Step S130, determining the position of the target diaphragm corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error.
And step S140, adjusting the diaphragm to the target diaphragm position, controlling imaging overlay measurement equipment, and performing overlay measurement on the overlay mark in the wafer to be measured.
It can be understood that the embodiment of the application quantifies the measurement state of the imaging overlay measurement device by using the device error, and the larger the device error is, the worse the measurement state of the device at the current test position is indicated. Based on the above, the device errors corresponding to all the test positions are counted, and the influence of the change of the test positions on the device errors is generalized, for example, the smaller the device errors corresponding to the test positions which are far away from the initial position, the farther the diaphragm is away from the initial position, and the better the corresponding device measurement state is. Based on this, a test position where the equipment error is minimum is determined as a target diaphragm position for measuring the wafer to be measured within a range in which the diaphragm is allowed to move.
In one possible implementation, determining the target diaphragm position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error comprises fitting each test position and the equipment error corresponding to the test position to obtain a target function corresponding to the wafer to be tested, wherein the target function represents the functional relationship between the test position and the equipment 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 diaphragm position corresponding to the wafer to be tested.
And performing data fitting on all the test positions (x i,yi) and the corresponding equipment errors TIS_M xi,yi of each test position to obtain a functional expression, namely an objective function, capable of representing the influence relation between the test positions and the equipment errors, and referring to the following expression (4).
(4)
Optionally, the objective function is fitted to a form of a binary quadratic function, as follows (5), so as to determine a minimum value of the device error from the objective function, thereby determining a test position corresponding to the diaphragm as the target diaphragm position when the imaging overlay measurement device is in an optimal measurement state.
(5)
Wherein, K 0、K1、K2、K3、K4、K5 represents each coefficient, and the specific value of the coefficient can be determined according to the data fitting result.
Further, based on the objective function of the formula (5), a test position (x i,yi) corresponding to the minimum value of the tis_m xi,yi is solved, wherein the test position is used as a target diaphragm position, and when the diaphragm is positioned at the position, the equipment measurement state of the imaging overlay measurement equipment is optimal. The control diaphragm moves to the target diaphragm position, and at the moment, the imaging overlay measurement equipment formally performs overlay measurement on the wafer to be measured.
In summary, in the overlay measurement method provided by the embodiment of the application, in response to the test instruction of the wafer to be tested, the diaphragm is moved to a plurality of test positions, and the error introduced by the device at each test position is measured, and because the imaging overlay measurement device only changes the position of the diaphragm, the error introduced by the device is defaulted to be the error introduced by the change of the position of the diaphragm. And determining the diaphragm position with the minimum equipment error according to the influence of the change of the diaphragm position on the equipment error, and taking the diaphragm position as the target position corresponding to the wafer to be measured.
And positioning the diaphragm of the imaging overlay measurement device to a target position, and performing overlay measurement on the wafer to be measured under the condition that the error introduced by the diaphragm is minimum, so that the accuracy of the overlay measurement is improved. Compared with the prior art, the method and the device for adjusting the diaphragm position according to the measurement result of the wafer to be measured enable the target diaphragm position to be more suitable for the wafer to be measured, based on the method and the device, if the wafer measured by the imaging overlay measurement device is replaced, the optimal diaphragm position can be positioned for the wafer in a personalized mode, and flexibility of the imaging overlay measurement device is improved.
The following describes an overlay measurement apparatus provided by an embodiment of the present application, and the overlay measurement apparatus described below and the overlay measurement method described above may be referred to correspondingly.
First, referring to fig. 4, an overlay measurement apparatus applied to a controller of an imaging overlay measurement device is described, and as shown in fig. 4, the overlay measurement apparatus may include:
a test position obtaining unit 100, configured to obtain a preset number of test positions corresponding to one diaphragm in the at least one diaphragm in response to a test instruction;
the error obtaining unit 200 is configured to control the diaphragm to sequentially move to each test position to perform overlay measurement on a wafer to be measured, and respectively obtain an equipment error of the imaging overlay measurement equipment at each test position, where the equipment error represents an error introduced by a position change of the diaphragm;
A target position determining unit 300, configured to determine a target diaphragm position corresponding to the wafer to be tested according to an influence of the change of the test position on the equipment error;
and the control measurement unit 400 is used for adjusting the diaphragm to the target diaphragm position, controlling the imaging overlay measurement equipment and performing overlay measurement on the overlay mark in the wafer to be measured.
In one possible implementation, the target position determining unit 300 includes:
The data fitting subunit is used for fitting each test position and the equipment error corresponding to the test position to obtain an objective function corresponding to the wafer to be tested, wherein the objective function represents the functional relationship between the test position and the equipment error corresponding to the wafer to be tested;
and the target position determining subunit is used for determining the corresponding test position when the target function is the minimum value as the target diaphragm position corresponding to the wafer to be tested.
In one possible implementation, the error acquisition unit 200 includes:
an overlay error acquisition subunit, configured to control the diaphragm to sequentially move to each test position to perform overlay measurement on a wafer to be tested, and respectively acquire an overlay error corresponding to each test position, where the overlay error includes overlay mark offset data corresponding to the wafer to be tested when a rotation angle is 0 ° and 180 °;
And the equipment error determining subunit is used for determining the equipment error corresponding to each test position according to the overlay error corresponding to each test position.
In one possible implementation, the device error determination subunit includes:
The offset obtaining subunit is configured 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 measured when the rotation angle of the wafer to be measured is 0 ° and a second offset corresponding to each overlay mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 180 °;
An initial equipment error determining subunit, configured to determine an initial equipment error corresponding to the overlay mark to be measured at the test position according to a difference value between the first offset and the second offset corresponding to the overlay mark to be measured;
And the equipment error determination subunit is used for determining the average value of the initial equipment errors corresponding to each overlay mark to be measured under the test position as the equipment error corresponding to the test position.
In one possible implementation, the test position acquisition unit 100 includes:
The initial position acquisition subunit is used for acquiring a pre-calibrated initial position corresponding to the diaphragm;
and the position adjustment subunit is used for adjusting the initial positions according to the preset stepping distance to obtain a preset number of test positions.
In summary, in the embodiment of the present application, in response to a test instruction of a wafer to be tested, the diaphragm is moved to a plurality of test positions, and the error introduced by the device at each test position is measured, and because the imaging overlay measurement device only has the position of the diaphragm changed, the error introduced by the device is defaulted to be the error introduced by the change of the position of the diaphragm. And determining the diaphragm position with the minimum equipment error according to the influence of the change of the diaphragm position on the equipment error, and taking the diaphragm position as the target position corresponding to the wafer to be measured.
And positioning the diaphragm of the imaging overlay measurement device to a target position, and performing overlay measurement on the wafer to be measured under the condition that the error introduced by the diaphragm is minimum, so that the accuracy of the overlay measurement is improved. Compared with the prior art, the method and the device for adjusting the diaphragm position according to the measurement result of the wafer to be measured enable the target diaphragm position to be more suitable for the wafer to be measured, based on the method and the device, if the wafer measured by the imaging overlay measurement device is replaced, the optimal diaphragm position can be positioned for the wafer in a personalized mode, and flexibility of the imaging overlay measurement device is improved.
The overlay measurement device provided by the embodiment of the application can be applied to overlay measurement equipment.
Fig. 5 shows a schematic diagram of the structure of an overlay measurement apparatus, referring to fig. 5, which 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.
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 complete communication with each other through the communication bus 30.
The processor 10 may be a central processing unit CPU, or an Application-specific integrated Circuit ASIC (Application SPECIFIC INTEGRATED Circuit), or one or more integrated circuits configured to implement embodiments of the present invention, or the like.
The memory 20 may comprise a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory) or the like, such as at least one disk memory.
The memory stores a program, and the processor can call the program stored in the memory, wherein the program is used for realizing each processing flow in the overlay measurement method.
The embodiment of the application also provides a computer storage medium, which can store a program suitable for being executed by a processor, and the program is used for realizing each processing flow in the alignment measurement method.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. An overlay measurement method, characterized by a controller applied to an imaging overlay measurement apparatus, the imaging overlay measurement apparatus comprising at least one diaphragm, the overlay measurement method comprising:
Responding to a test instruction, and acquiring a preset number of test positions corresponding to one diaphragm in the at least one diaphragm;
The diaphragm is controlled to sequentially move to each test position to carry out overlay measurement on a wafer to be measured, and equipment errors of the imaging overlay measurement equipment at each test position are respectively obtained, wherein the equipment errors represent errors introduced by position changes of the diaphragm;
determining a target diaphragm position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error;
and adjusting the diaphragm to the target diaphragm position, controlling the imaging overlay measurement equipment, and performing overlay measurement on the overlay mark in the wafer to be measured.
2. The overlay measurement method according to claim 1, wherein determining the target stop position corresponding to the wafer to be measured according to the influence of the change of the test position on the equipment error comprises:
Fitting each test position and the equipment error corresponding to the test position to obtain an objective function corresponding to the wafer to be tested, wherein the objective function represents a functional relationship between the test position and the equipment error corresponding to the wafer to be tested;
And determining the corresponding test position when the objective function is the minimum value as the corresponding target diaphragm position of the wafer to be tested.
3. The overlay measurement method according to claim 1, wherein the controlling the diaphragm to move to each of the test positions in turn performs overlay measurement on the wafer to be measured, and respectively obtains an equipment error of the imaging overlay measurement equipment at each of the test positions, includes:
The diaphragm is controlled to sequentially move to each test position to carry out overlay measurement on the wafer to be tested, and overlay errors corresponding to each test position are respectively obtained, wherein the overlay errors comprise overlay mark offset data corresponding to the wafer to be tested when the rotation angle of the wafer to be tested is 0 DEG and 180 DEG;
And determining the equipment error corresponding to each test position according to the overlay error corresponding to each test position.
4. The overlay measurement method of claim 3, wherein determining the device error for each of the test positions based on the overlay error for each of the test positions comprises:
Acquiring a first offset corresponding to each overlay mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 0 degrees and a second offset corresponding to each overlay mark to be measured in the wafer to be measured when the rotation angle of the wafer to be measured is 180 degrees from the overlay errors corresponding to the test positions;
Determining an initial equipment error corresponding to the overlay mark to be measured at the test position according to the difference value of the first offset and the second offset corresponding to the overlay mark to be measured;
And determining the average value of the initial equipment errors corresponding to each overlay mark to be measured at the test position as the equipment error corresponding to the test position.
5. The overlay measurement method according to claim 1, wherein the obtaining a preset number of test positions corresponding to one diaphragm in the at least one diaphragm comprises:
Acquiring a pre-calibrated initial position corresponding to one diaphragm in the at least one diaphragm;
and adjusting the initial positions according to the preset stepping distance to obtain a preset number of test positions.
6. An overlay measurement apparatus, characterized by a controller for an imaging overlay measurement device, the imaging overlay measurement device comprising at least one aperture, the overlay measurement apparatus comprising:
the test position acquisition unit is used for responding to the test instruction and acquiring a preset number of test positions corresponding to one diaphragm in the at least one diaphragm;
the error acquisition unit is used for controlling the diaphragm to sequentially move to each test position to carry out overlay measurement on a wafer to be measured, and respectively acquiring equipment errors of the imaging overlay measurement equipment at each test position, wherein the equipment errors represent errors introduced by the position change of the diaphragm;
The target position determining unit is used for determining a target diaphragm position corresponding to the wafer to be tested according to the influence of the change of the test position on the equipment error;
And the control measurement unit is used for adjusting the diaphragm to the target diaphragm position, controlling the imaging overlay measurement equipment and performing overlay measurement on the overlay mark in the wafer to be measured.
7. The overlay measurement apparatus of claim 6, wherein the target position determination unit comprises:
The data fitting subunit is used for fitting each test position and the equipment error corresponding to the test position to obtain an objective function corresponding to the wafer to be tested, wherein the objective function represents the functional relationship between the test position and the equipment error corresponding to the wafer to be tested;
and the target position determining subunit is used for determining the corresponding test position when the target function is the minimum value as the target diaphragm position corresponding to the wafer to be tested.
8. The overlay measurement apparatus according to claim 6, wherein the error acquisition unit comprises:
an overlay error acquisition subunit, configured to control the diaphragm to sequentially move to each test position to perform overlay measurement on a wafer to be tested, and respectively acquire an overlay error corresponding to each test position, where the overlay error includes overlay mark offset data corresponding to the wafer to be tested when a rotation angle is 0 ° and 180 °;
And the equipment error determining subunit is used for determining the equipment error corresponding to each test position according to the overlay error corresponding to each test position.
9. An overlay measurement apparatus comprising at least one processor and a memory coupled to the processor, wherein:
The memory is used for storing a computer program;
The processor is configured to execute the computer program to enable the overlay measurement apparatus to implement the overlay measurement method according to any one of claims 1 to 5.
10. A computer storage medium carrying one or more computer programs which, when executed by an overlay measurement apparatus, enable the overlay measurement apparatus to implement the overlay measurement method of any one of claims 1 to 5.
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| CN101236362A (en) * | 2008-01-29 | 2008-08-06 | 北京理工大学 | On-line detection method for wave aberration of projection objective lens in lithography machine |
| CN103777467A (en) * | 2012-10-19 | 2014-05-07 | 上海微电子装备有限公司 | Overlay error measurement apparatus and method |
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| EP1962138B1 (en) * | 2007-02-23 | 2011-12-14 | Imec | Systems and methods for UV lithography |
| NL1036245A1 (en) * | 2007-12-17 | 2009-06-18 | Asml Netherlands Bv | Diffraction based overlay metrology tool and method or diffraction based overlay metrology. |
| CN112015056B (en) * | 2020-07-29 | 2023-01-03 | 中国科学院微电子研究所 | Overlay offset value correction method, electronic device and computer-readable storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101236362A (en) * | 2008-01-29 | 2008-08-06 | 北京理工大学 | On-line detection method for wave aberration of projection objective lens in lithography machine |
| CN103777467A (en) * | 2012-10-19 | 2014-05-07 | 上海微电子装备有限公司 | Overlay error measurement apparatus and method |
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