Alignment mark positioning compensation method

Abstract

The invention provides an alignment mark positioning compensation method, which comprises the following steps that: a main camera and an auxiliary camera are provided to measure each alignment mark on a wafer on a motion table, and the multiplying power of the main camera is greater than that of the auxiliary camera; calculating a loading error and a mapping distance of a specified adjacent alignment mark under a motion table coordinate system by using an auxiliary camera; and calculating the coordinate of any alignment mark according to the loading error and the mapping distance, and measuring the position deviation of the any alignment mark by using the main camera to dynamically compensate the coordinate calculation of the next any alignment mark.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a method for positioning an alignment mark. Background Art

[0002] In high-precision measurement systems, high-magnification lenses are often used to improve measurement accuracy, but this also limits the camera's field of view. If there is a deviation in the position of the alignment mark, the alignment mark will be partially visible or completely invisible in the camera's field of view, resulting in the alignment mark being unable to be identified. Therefore, it is necessary to quickly and accurately locate the position of the alignment mark.

[0003] According to the prior art, the three-point method is generally used to locate the coordinate position of each alignment mark, that is, by measuring the position of three specific marks, the position of other marks is inferred. In actual use, a large-field-of-view, low-magnification camera is usually used to quickly identify these three marks. However, the mark positions measured by a large-field-of-view, low-magnification camera will have measurement errors, and the prior art does not take into account the errors of the film loading and the motion errors of the motion stage. Therefore, these errors will cause position deviations in the calculated positions of other marks, which will ultimately make the marks incomplete in the camera's field of view or even out of the camera's field of view, and the marks cannot be identified. Summary of the invention

[0004] In order to overcome the defects of the prior art, the present invention dynamically compensates the coordinates of the alignment mark according to the loading error and the position deviation of the front and rear alignment marks, so that the position of the alignment mark can be located more accurately, ensuring that the complete alignment mark can be identified within the camera field of view each time measurement is performed.

[0005] The present invention provides an alignment mark positioning compensation method, comprising the following steps:

[0006] Providing a main camera and a sub-camera to measure each alignment mark on the wafer located on the moving stage, wherein the magnification of the main camera is greater than the magnification of the sub-camera;

[0007] The secondary camera is used to calculate the loading error and the mapping distance of the specified adjacent alignment marks in the motion stage coordinate system;

[0008] The coordinates of any alignment mark are calculated according to the loading error and the mapping distance, and the position deviation of the arbitrary alignment mark is measured by the main camera to dynamically compensate for the coordinate calculation of the next arbitrary alignment mark.

[0009] In one embodiment, the designated adjacent alignment marks are a first designated alignment mark, a second designated alignment mark and a third designated alignment mark, wherein the second designated alignment mark is adjacent to the first designated alignment mark in the left-right direction, and the third designated alignment mark is adjacent to the first designated alignment mark in the up-down direction.

[0010] In one embodiment, the present invention further comprises:

[0011] Get the length value ShotSizeX and the width value ShotSizeY of each die of the wafer.

[0012] In one embodiment, calculating the loading error using the secondary camera includes:

[0013] Calculate the motion stage coordinates (CenterX, CenterY) of a first designated alignment mark of a standard wafer under the auxiliary camera, and calculate the motion stage coordinates (x0, y0) of the first designated alignment mark of the standard wafer under the main camera;

[0014] Calculating the motion stage coordinates (X0, Y0) of a first designated alignment mark of a wafer under test under the secondary camera, wherein the position of the first designated alignment mark of the wafer under test corresponds to the position of the first designated alignment mark of the standard wafer;

[0015] The wafer loading errors ΔX and ΔY are obtained according to the difference in the motion stage coordinates of the first designated alignment marks of the standard wafer and the wafer under test under the auxiliary camera.

[0016] In one embodiment, the step of obtaining the wafer loading errors ΔX and ΔY according to the difference in the motion stage coordinates of the first designated alignment mark of the standard wafer and the wafer under test under the secondary camera comprises:

[0017] The plate loading errors ΔX and ΔY are calculated according to the formulas ΔX=X0-CenterX; and ΔY=Y0-CenterY.

[0018] In one embodiment, the step of calculating the motion stage coordinates (CenterX, CenterY) of a first designated alignment mark of a standard wafer under the secondary camera includes:

[0019] Use the secondary camera to find the first designated alignment mark of the standard wafer, move it into the field of view of the secondary camera, select the first designated alignment mark area and make a template image of the secondary camera; match through the template image, identify and locate the image of the first designated alignment mark, calculate the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the secondary camera, and move the image of the first designated alignment mark to the center of the field of view of the secondary camera according to the coordinate deviation, and record the motion stage coordinates (CenterX, CenterY) corresponding to the first designated alignment mark.

[0020] In one embodiment, the step of calculating the motion stage coordinates (x0, y0) of the first designated alignment mark of the standard wafer under the main camera includes:

[0021] According to the fixed physical position relationship between the main camera and the auxiliary camera, the first designated alignment mark is moved into the field of view of the main camera, and the first designated alignment mark area is framed to produce a template image of the main camera; matching is performed through the template image to identify and locate the image of the first designated alignment mark, and the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the main camera is calculated, and the image of the first designated alignment mark is moved to the center of the field of view of the main camera according to the coordinate deviation, and the motion stage coordinates (x0, y0) corresponding to the first designated alignment mark are recorded.

[0022] In one embodiment, the step of calculating the mapping distance between the designated adjacent alignment marks in the motion stage coordinate system comprises:

[0023] Calculate the motion stage coordinates (X1, Y1) of the second designated alignment mark of the wafer under test under the auxiliary camera;

[0024] According to the motion stage coordinates (X1, Y1) of the second designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark, the mapping distances ΔXX and ΔXY between the two in the X-axis direction and the Y-axis direction of the motion stage coordinates are calculated;

[0025] Calculate the motion stage coordinates (X2, Y2) of the third designated alignment mark of the wafer under test under the auxiliary camera;

[0026] According to the motion stage coordinates (X2, Y2) of the third designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark, the mapping distances ΔYX, ΔYY between the two in the X-axis direction and the Y-axis direction of the motion stage coordinates are calculated.

[0027] In one embodiment, the step of calculating the motion stage coordinates (X1, Y1) of the second designated alignment mark of the wafer under test under the secondary camera includes:

[0028] Move the motion stage to the coordinates (X0+ShotSizeX, Y0), identify and locate the image of the second designated alignment mark within the field of view of the secondary camera through template matching, calculate the coordinate deviation between the image coordinates of the second designated alignment mark and the exact center of the field of view of the secondary camera, move the image of the second designated alignment mark to the exact center of the field of view of the secondary camera, and obtain the motion stage coordinates (X1, Y1) of the second designated alignment mark.

[0029] In one embodiment, the step of calculating the mapping distances ΔXX and ΔXY between the second designated alignment mark and the first designated alignment mark in the X-axis direction and the Y-axis direction of the motion stage coordinates according to the motion stage coordinates (X1, Y1) of the second designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark comprises:

[0030] The mapping distances ΔXX and ΔXY are calculated according to the formulas ΔXX=X1-X0, ΔXY=Y1-Y0.

[0031] In one embodiment, the step of calculating the motion stage coordinates (X2, Y2) of the third designated alignment mark of the wafer under test under the secondary camera includes:

[0032] Move the motion stage to (X0, Y0 + ShotSizeY), identify and locate the image of the third designated alignment mark within the field of view of the secondary camera through template matching, calculate the coordinate deviation between the image coordinates of the third designated alignment mark and the center of the field of view, and move the image of the third designated alignment mark to the center of the field of view according to the coordinate deviation, and obtain the motion stage coordinates (X2, Y2) of the third designated alignment mark (for example, alignment mark (0, 1)).

[0033] In one embodiment, the step of calculating the mapping distances ΔYX, ΔYY between the two in the X-axis direction and the Y-axis direction of the motion stage coordinates according to the motion stage coordinates (X2, Y2) of the third designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark comprises:

[0034] The mapping distances ΔYX, ΔYY are calculated according to the formulas ΔYX=X2-X0, ΔYY=Y2-Y0.

[0035] In one embodiment, the step of calculating the coordinates of any alignment mark according to the loading error and the mapping distance, and using a main camera to measure the position deviation of the arbitrary alignment mark to dynamically compensate for the coordinate calculation of the next arbitrary alignment mark includes:

[0036] a. Calculate the coordinates (X, Y) of any alignment mark according to formula (1):

[0037] X=x0-ΔX+N*ΔXX+M*ΔYX+offsetX

[0038] Y=y0-ΔY+N*ΔXY+M*ΔYY+offsetY Formula (1)

[0039] in,

[0040] (X,Y): coordinates of the motion stage of any alignment mark (alignment mark (N,M)) under the main camera;

[0041] (x0, y0): coordinates of the motion stage of the first specified alignment mark under the main camera;

[0042] (ΔX, Δt): the loading error of the first designated alignment mark under the secondary camera;

[0043] (ΔXX, ΔXY): The mapping distance of a single alignment mark moved laterally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔXX and ΔXY between adjacent alignment marks on the left and right sides in the X-axis direction and the Y-axis direction);

[0044] (ΔYX, ΔYY): The mapping distance of a single alignment mark moved longitudinally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔYX and ΔYY between the upper and lower adjacent alignment marks in the X-axis direction and the Y-axis direction);

[0045] (N,M): The corresponding row and column numbers of any alignment mark on the wafer;

[0046] (offsetX, offsetY): the position offset on the X-axis and Y-axis under the main camera;

[0047] b. Update the motion stage coordinates of the arbitrary alignment mark under the main camera to (FoundX, FoundY), and then update the offsetX and offsetY values.

[0048] c. Repeat steps a and b to calculate the coordinates of any other alignment marks of the wafer being measured.

[0049] In one embodiment, the step b comprises:

[0050] When the coordinates of the first arbitrary alignment mark are calculated using formula (1), offsetX and offsetY are initialized to 0. After the coordinates are calculated, the motion stage is moved to the coordinates. The image of the first arbitrary alignment mark is identified and located within the field of view of the main camera by template matching, and the coordinate deviation between the image coordinates of the first arbitrary alignment mark and the center of the field of view of the main camera is calculated. The image of the first arbitrary alignment mark is moved to the center of the field of view of the main camera according to the coordinate deviation, and the motion stage coordinates (FoundX, FoundY) of the first arbitrary alignment mark under the main camera are obtained. The offsetX and offsetY values ​​are updated according to the formulas offsetX=offsetX+FoundX-X, offsetY=offsetY+FoundY-Y.

[0051] According to the alignment mark positioning compensation method of the present invention, after each wafer loading, the auxiliary camera sequentially identifies and locates the three selected alignment marks, and calculates the coordinates of each alignment mark on the wafer according to the formula of the present solution. Then, the camera moves to the calculated coordinate position, and the complete alignment mark can be seen in the field of view of the main camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above invention content and the following specific embodiments of the present invention will be better understood when read in conjunction with the accompanying drawings. It should be noted that the accompanying drawings are only examples of the claimed invention. In the accompanying drawings, the same reference numerals represent the same or similar elements.

[0053] Figure 1 showing a wafer map;

[0054] Figure 2 An optical system according to an embodiment of the present invention is shown;

[0055] Figure 3 The main camera field of view of an alignment mark according to an embodiment of the present invention is shown, wherein the intersection of the horizontal and vertical dashed lines is the center of the field of view;

[0056] Figure 4 The secondary camera field of view of an alignment mark according to an embodiment of the present invention is shown, wherein the intersection of the horizontal and vertical dashed lines is the center of the field of view;

[0057] Figure 5 A flow chart of an alignment mark positioning compensation method according to an embodiment of the present invention is shown;

[0058] Figure 6 shows an alignment mark image profile according to an embodiment of the present invention;

[0059] Figure 7 A schematic diagram showing the relationship between the center of the alignment mark image and the center of the camera according to an embodiment of the present invention;

[0060] Figure 8 Three alignment marks in the motion stage coordinate system according to an embodiment of the present invention are shown. DETAILED DESCRIPTION

[0061] The detailed features and advantages of the present invention are described in detail in the specific embodiments below, and the content is sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly, and according to the description, claims and drawings disclosed in this specification, those skilled in the art can easily understand the relevant purposes and advantages of the present invention. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this embodiment. On the contrary, the purpose of introducing the invention in conjunction with the embodiment is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0062] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal" and "vertical" used in the following description should be understood as the directions shown in the paragraph and the related drawings. Such relative terms are only used for the convenience of description and do not mean that the device described therein must be manufactured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0064] It is understood that although the terms "first", "second", "third", etc. may be used herein to describe various components, channels, components, regions, layers and / or parts, these components, channels, components, regions, layers and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, channels, components, regions, layers and / or parts. In addition, the terms "first", "second", "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0065] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0066] In some embodiments, numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values ​​is as accurate as possible within the feasible range.

[0067] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0068] Figure 1 A wafer map is shown. A wafer includes multiple dies, which form a group of die matrices. Each die corresponds to an alignment mark, and the alignment mark can be used to locate the die in the wafer. Each alignment mark has its own row and column number. For example, the row and column number of the center alignment mark is (0, 0), the row and column number of the alignment mark adjacent to its right is (1, 0), and the row and column number of the alignment mark adjacent to its upper side is (0, 1). Therefore, (N, M) can be used to represent the row and column number corresponding to each alignment mark on the wafer. The length and width of each die are ShotSizeX and ShotSizeY respectively.

[0069] Figure 2 2 shows an optical system according to an embodiment of the present invention. The optical system of the present invention is a dual-camera optical system. The dual-camera optical system includes a main camera 201 and a secondary camera 202, wherein the secondary camera 202 uses a low-magnification lens, which has a large field of view and is therefore used to calculate alignment parameters; the main camera uses a high-magnification lens, which has high precision and is therefore used for high-precision measurement.

[0070] In one embodiment, the field of view of the primary camera is 100um*100um, and the field of view of the secondary camera is 1mm*1mm.

[0071] like Figure 2 As shown, the wafer 203 is set on the moving stage 204, and the main camera 201 and the auxiliary camera 202 are located above the wafer 203 for observation, wherein the physical position relationship between the main camera 201 and the auxiliary camera 202 is fixed.

[0072] Figure 3 The main camera field of view of an alignment mark according to an embodiment of the present invention is shown, wherein the intersection of the horizontal and vertical dashed lines is the center of the field of view.

[0073] Figure 4 The secondary camera field of view of an alignment mark according to an embodiment of the present invention is shown, wherein the intersection of the horizontal and vertical dashed lines is the center of the field of view.

[0074] Figure 5 A flow chart of an alignment mark positioning compensation method according to an embodiment of the present invention is shown.

[0075] The alignment mark positioning compensation method comprises the following steps:

[0076] Step 501: Obtain the length and width information of each die of the wafer, ie, ShotSizeX and ShotSizeY values.

[0077] Step 502: Calculate the motion stage coordinates (CenterX, CenterY) of the first designated alignment mark of the standard wafer under the auxiliary camera.

[0078] In one embodiment, a wafer is placed on a moving table as a standard wafer, and a first designated alignment mark (e.g., alignment mark (0,0)) of the wafer is found by a secondary camera, and the wafer is moved into the field of view of the secondary camera, and the first designated alignment mark area is framed and a template image of the secondary camera is prepared; the outline of the template image (e.g., Figure 6 The center point image coordinates of the first designated alignment mark are defined as the image coordinates of the alignment mark; the image of the first designated alignment mark is identified and located through template image matching, the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the secondary camera's field of view is calculated, and the image of the first designated alignment mark is moved to the center of the secondary camera's field of view, and the motion stage coordinates (CenterX, CenterY) corresponding to the first designated alignment mark are recorded.

[0079] Step 503: Calculate the motion stage coordinates (x0, y0) of the first designated alignment mark of the standard wafer under the main camera.

[0080] In one embodiment, according to the fixed physical position relationship between the main camera and the auxiliary camera, the first designated alignment mark (for example, the alignment mark (0,0)) is moved into the field of view of the main camera, and the first designated alignment mark area is framed to produce a template image of the main camera; through template image matching, the image of the first designated alignment mark is identified and located, and the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the main camera is calculated, and the alignment mark image is moved to the center of the field of view of the main camera according to the coordinate deviation, and the motion stage coordinates (x0, y0) corresponding to the first designated alignment mark are recorded.

[0081] Step 504: Calculate the motion stage coordinates (X0, Y0) of the first designated alignment mark of the wafer under test under the auxiliary camera.

[0082] In one embodiment, a wafer to be measured is placed on a moving stage, and the moving stage is moved to the position (CenterX, CenterY). The image of the first designated alignment mark is identified and located in the field of view of the secondary camera by template matching, and the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the secondary camera is calculated, and the image of the first designated alignment mark is moved to the center of the field of view of the secondary camera according to the coordinate deviation, and the moving stage coordinates (X0, Y0) of the first designated alignment mark (for example, alignment mark (0,0)) corresponding to the measured wafer are obtained.

[0083] It should be noted that the position of the first designated alignment mark of the wafer under test corresponds to the position of the first designated alignment mark of the standard wafer. For example, both are center alignment marks.

[0084] Step 505: Calculate wafer loading errors ΔX and ΔY according to the difference in motion stage coordinates of the first designated alignment mark of the standard wafer and the wafer under test under the auxiliary camera.

[0085] In one embodiment, the loading errors ΔX and ΔY are calculated according to the formulas ΔX=X0-CenterX, ΔY=Y0-CenterY.

[0086] Normally, before the wafer is placed on the moving table, the center and angle of the wafer will be measured by the wafer pre-aligner. This wafer pre-aligner has a precision error. The common wafer pre-aligner has a precision of 100um-300um and an angle of 0.05 degrees-0.1 degrees. In addition, the wafer is placed on the moving table by a robotic arm, and the movement of the robotic arm also has a precision error. Due to the errors of the two, the position of each wafer placed on the moving table is different. The coordinates of the standard wafer on the moving table are used as the standard. The deviation of the coordinates of other wafer placements and the coordinates of the standard wafer is called the wafer loading error. Therefore, if the accuracy of the alignment mark positioning is to be improved, it is necessary to consider the loading error. When the loading error is very large, when the next wafer is measured, the complete alignment mark may not be recognized in the main camera field of view. Therefore, it is more reasonable for the present invention to use a secondary camera with a low magnification lens to measure the loading error.

[0087] Step 506: Calculate the motion stage coordinates (X1, Y1) of the second designated alignment mark of the wafer under test under the auxiliary camera, where the second designated alignment mark is adjacent to the first designated alignment mark in the left-right direction (due to the rotation angle between the wafer and the motion stage, the left-right direction is not necessarily the X-axis direction).

[0088] In one embodiment, the motion stage is moved to (X0+ShotSizeX,Y0), the image of the second designated alignment mark is identified and located within the field of view of the secondary camera through template matching, the coordinate deviation between the image coordinates of the second designated alignment mark and the exact center of the field of view of the secondary camera is calculated, and the image of the second designated alignment mark is moved to the exact center of the field of view of the secondary camera to obtain the motion stage coordinates (X1,Y1) of the second designated alignment mark (for example, alignment mark (1,0)).

[0089] Step 507: Calculate the distances ΔXX and ΔXY between the second designated alignment mark and the first designated alignment mark according to the motion stage coordinates (X1, Y1) and the motion stage coordinates (X0, Y0).

[0090] In one embodiment, ΔXX and ΔXY are calculated based on the first designated alignment mark (alignment mark (0,0)) and the second designated alignment mark (alignment mark (1,0)). Calculation formula: ΔXX = X1-X0, ΔXY = Y1-Y0.

[0091] Step 508: Calculate the motion stage coordinates (X2, Y2) of the third designated alignment mark of the wafer under test under the auxiliary camera, where the third designated alignment mark is adjacent to the first designated alignment mark in the up and down direction (due to the rotation angle between the wafer and the motion stage, the up and down direction is not necessarily the Y-axis direction).

[0092] In one embodiment, the motion stage is moved to (X0, Y0 + ShotSizeY), the image of the third designated alignment mark is identified and located within the field of view of the secondary camera through template matching, the coordinate deviation between the image coordinates of the third designated alignment mark and the exact center of the field of view is calculated, and the image of the third designated alignment mark is moved to the exact center of the field of view based on the coordinate deviation to obtain the motion stage coordinates (X2, Y2) of the third designated alignment mark (for example, alignment mark (0,1)).

[0093] Step 509: Calculate the distance ΔYX, ΔYY between the third designated alignment mark and the first designated alignment mark according to the motion stage coordinates (X2, Y2) and the motion stage coordinates (X0, Y0).

[0094] In one embodiment, ΔYX and ΔYY are calculated based on the first designated alignment mark (alignment mark (0,0)) and the third designated alignment mark (alignment mark (0,1)). Calculation formula: ΔYX = X2-X0, ΔYY = Y2-Y0.

[0095] Step 510: Calculate the coordinates (X, Y) of any alignment mark according to the following formula:

[0096] X=x0-ΔX+N*ΔXX+M*ΔYX+offsetX

[0097] Y=y0-ΔY+N*ΔXY+M*ΔYY+offsetY Formula (1)

[0098] in,

[0099] (X,Y): coordinates of the motion stage of any alignment mark (alignment mark (N,M)) under the main camera;

[0100] (x0, y0): coordinates of the motion stage of the first specified alignment mark under the main camera;

[0101] (ΔX, ΔY): the loading error of the first designated alignment mark under the secondary camera;

[0102] (ΔXX, ΔXY): The mapping distance of a single alignment mark moved laterally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔXX and ΔXY between adjacent alignment marks on the left and right sides in the X-axis direction and the Y-axis direction);

[0103] (ΔYX, ΔYY): The mapping distance of a single alignment mark moved longitudinally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔYX and ΔYY between the upper and lower adjacent alignment marks in the X-axis direction and the Y-axis direction);

[0104] (N,M): The corresponding row and column numbers of any alignment mark on the wafer;

[0105] (offsetX, offsetY): dynamic compensation of position offset of adjacent alignment marks on the X-axis and Y-axis under the main camera;

[0106] Step 511: Under the main camera, update the motion stage coordinates of the arbitrary alignment mark to (FoundX, FoundY), and then update the offsetX, offsetY values. That is, use the position deviation of the previous alignment mark to compensate the position of the next arbitrary alignment mark.

[0107] Specifically, when using formula (1) to calculate the coordinates of the first arbitrary alignment mark, offsetX and offsetY are initialized to 0. After the coordinates are calculated, the motion stage is moved to the coordinates. The image of the alignment mark is identified and located within the field of view of the main camera through template matching, and the coordinate deviation between the image coordinates of the alignment mark and the center of the field of view is calculated. Based on the coordinate deviation, the image of the alignment mark is moved to the center of the field of view of the main camera, and the motion stage coordinates (FoundX, FoundY) of the alignment mark under the main camera are obtained. According to the formula offsetX=offsetX+FoundX-X, offsetY=offsetY+FoundY-Y, the offsetX and offsetY values ​​are updated.

[0108] Step 512: Repeat steps 510 and 511 to sequentially calculate the coordinates of any other alignment marks of the wafer being tested.

[0109] Step 513: When measuring other wafers, repeat steps 504 to 512 to perform measurement.

[0110] Figure 6 An alignment mark image profile according to an embodiment of the present invention is shown.

[0111] Figure 7 A schematic diagram showing the relationship between the center of the alignment mark image and the center of the camera according to an embodiment of the present invention is shown. The small dot represents the center of the alignment mark image contour, and the two dotted lines represent the center of the camera field of view. In the field of view of the secondary camera, the relative distances between the intersection of the small dot and the dotted line on the X-axis and Y-axis are converted to ΔX and ΔY in the motion stage coordinate system, respectively. In the field of view of the primary camera, the relative distances between the intersection of the small dot and the dotted line on the X-axis and Y-axis are converted to offsetX and offsetY in the motion stage coordinate system, respectively.

[0112] Figure 8 Three alignment marks in the motion stage coordinate system according to an embodiment of the present invention are shown. The three small dots represent the coordinate positions of the first designated alignment mark, the second designated alignment mark, and the third designated alignment mark on the wafer on the motion stage (the motion stage coordinates when the alignment mark image center coincides with the field of view center) and the mapping of the distances between them on the X-axis and the Y-axis ΔXX, ΔXY, ΔYX, ΔYY.

[0113] Those skilled in the art will appreciate that the various illustrative components, modules, blocks, units, circuits, systems, and steps described in conjunction with the embodiments disclosed herein may be implemented by hardware, software (including firmware, resident software, microcode, etc.), or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, modules, blocks, units, circuits, systems, and steps are described above in general terms in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0114] Flowcharts are used in the present application to illustrate the operations or steps performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations or steps are not necessarily performed accurately in order. On the contrary, various operations or steps may be processed in reverse order or simultaneously. At the same time, other operations or steps may be added to these processes, or one or more operations or steps may be removed from these processes.

[0115] Unless explicitly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in the present application are not intended to limit the order of the processes and methods of the present application.

[0116] Furthermore, aspects of the present application may take the form of a computer product embodied in one or more computer-readable media including computer-readable program code.

[0117] A computer readable signal medium may include a propagated data signal containing computer program code, such as in baseband or as part of a carrier wave. The propagated signal may have a variety of forms, including electromagnetic, optical, etc., or a suitable combination. A computer readable signal medium may be any computer readable medium other than a computer readable storage medium, which may be connected to an instruction execution system, device or apparatus to communicate, propagate or transmit a program for use. The program code on the computer readable signal medium may be propagated through any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0118] The computer program coding required for the operation of each part of the application can be written in any one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, etc., conventional procedural programming languages ​​such as C language, Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby and Groovy, or other programming languages, etc. The program coding can be run completely on the user's computer, or run on the user's computer as an independent software package, or run partly on the user's computer and partly on the remote computer, or run completely on the remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any network form, such as a local area network (LAN) or a wide area network (WAN), or connected to an external computer (e.g., via the Internet), or in a cloud computing environment, or used as a service such as software as a service (SaaS).

[0119] Those skilled in the art will appreciate that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips cited throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0120] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be directly embodied in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. In an alternative, a processor and a storage medium may reside in a user terminal as discrete components.

[0121] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0122] The terms and expressions used above are for descriptive purposes only, and the present invention should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the illustrations and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, changes and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

[0123] Similarly, it should be noted that in order to simplify the description of the disclosure of this application and thus facilitate the understanding of one or more embodiments of the invention, in the foregoing description of the embodiments of this application, multiple features are sometimes combined into one embodiment, drawing or description thereof. However, this disclosure method does not mean that the features required by the object of this application are more than the features mentioned in the claims.

[0124] Similarly, it should be pointed out that although the present invention has been described with reference to the current specific embodiments, ordinary technicians in this technical field should realize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions may be made without departing from the spirit of the present invention. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present invention, they will fall within the scope of the claims of this application.

Claims

1. A method for compensating alignment mark positioning, characterized in that: include: Providing a main camera and a sub-camera to measure each alignment mark on the wafer located on the moving stage, wherein the magnification of the main camera is greater than the magnification of the sub-camera; The secondary camera is used to calculate the loading error and the mapping distance of the specified adjacent alignment marks in the motion stage coordinate system; The coordinates of any alignment mark are calculated according to the loading error and the mapping distance, and the position deviation of the arbitrary alignment mark is measured by the main camera to dynamically compensate for the coordinate calculation of the next arbitrary alignment mark.

2. The alignment mark positioning compensation method according to claim 1, characterized in that: The designated adjacent alignment marks are a first designated alignment mark, a second designated alignment mark and a third designated alignment mark, wherein the second designated alignment mark is adjacent to the first designated alignment mark in the left-right direction, and the third designated alignment mark is adjacent to the first designated alignment mark in the up-down direction.

3. The alignment mark positioning compensation method according to claim 1, characterized in that: Also includes: Get the length value ShotSizeX and the width value ShotSizeY of each die of the wafer.

4. The alignment mark positioning compensation method according to claim 2, characterized in that: The calculation of the loading error using the secondary camera includes: Calculate the motion stage coordinates (CenterX, CenterY) of a first designated alignment mark of a standard wafer under the auxiliary camera, and calculate the motion stage coordinates (x0, y0) of the first designated alignment mark of the standard wafer under the main camera; Calculating the motion stage coordinates (X0, Y0) of a first designated alignment mark of a wafer under test under the secondary camera, wherein the position of the first designated alignment mark of the wafer under test corresponds to the position of the first designated alignment mark of the standard wafer; The wafer loading errors ΔX and ΔY are obtained according to the difference in the motion stage coordinates of the first designated alignment marks of the standard wafer and the wafer under test under the auxiliary camera.

5. The alignment mark positioning compensation method according to claim 4, characterized in that: The step of obtaining the wafer loading errors ΔX and ΔY according to the difference in the motion stage coordinates of the first designated alignment mark of the standard wafer and the wafer under test under the auxiliary camera comprises: The upper sheet errors ΔX and ΔY are calculated according to the formulas ΔX=X0-CenterX; and ΔY=Y0-CenterY.

6. The alignment mark positioning compensation method according to claim 4, characterized in that: The step of calculating the motion stage coordinates (CenterX, CenterY) of a first designated alignment mark of a standard wafer under the auxiliary camera comprises: Use the secondary camera to find the first designated alignment mark of the standard wafer, move it into the field of view of the secondary camera, select the first designated alignment mark area and make a template image of the secondary camera; match through the template image, identify and locate the image of the first designated alignment mark, calculate the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the secondary camera, and move the image of the first designated alignment mark to the center of the field of view of the secondary camera according to the coordinate deviation, and record the motion stage coordinates (CenterX, CenterY) corresponding to the first designated alignment mark.

7. The alignment mark positioning compensation method according to claim 4, characterized in that: The step of calculating the motion stage coordinates (x0, y0) of the first designated alignment mark of the standard wafer under the main camera comprises: According to the fixed physical position relationship between the main camera and the auxiliary camera, the first designated alignment mark is moved into the field of view of the main camera, and the first designated alignment mark area is framed to produce a template image of the main camera; matching is performed through the template image to identify and locate the image of the first designated alignment mark, and the coordinate deviation between the image coordinates of the first designated alignment mark and the center of the field of view of the main camera is calculated, and the image of the first designated alignment mark is moved to the center of the field of view of the main camera according to the coordinate deviation, and the motion stage coordinates (x0, y0) corresponding to the first designated alignment mark are recorded.

8. The alignment mark positioning compensation method according to claim 4, characterized in that: The step of calculating the mapping distance of the specified adjacent alignment marks in the motion stage coordinate system comprises: Calculate the motion stage coordinates (X1, Y1) of the second designated alignment mark of the wafer under test under the auxiliary camera; According to the motion stage coordinates (X1, Y1) of the second designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark, the mapping distances ΔXX and ΔXY between the two in the X-axis direction and the Y-axis direction of the motion stage coordinates are calculated; Calculate the motion stage coordinates (X2, Y2) of the third designated alignment mark of the wafer under test under the auxiliary camera; According to the motion stage coordinates (X2, Y2) of the third designated alignment mark and the motion stage coordinates (X0, Y0) of the first designated alignment mark, the mapping distances ΔYX, ΔYY between the two in the X-axis direction and the Y-axis direction of the motion stage coordinates are calculated.

9. The alignment mark positioning compensation method according to claim 8, characterized in that: The step of calculating the motion stage coordinates (X1, Y1) of the second designated alignment mark of the wafer under test under the auxiliary camera comprises: Move the motion stage to the coordinates (X0+ShotSizeX, Y0), identify and locate the image of the second designated alignment mark within the field of view of the secondary camera through template matching, calculate the coordinate deviation between the image coordinates of the second designated alignment mark and the exact center of the field of view of the secondary camera, move the image of the second designated alignment mark to the exact center of the field of view of the secondary camera, and obtain the motion stage coordinates (X1, Y1) of the second designated alignment mark.

10. The alignment mark positioning compensation method according to claim 8, characterized in that: The step of calculating the mapping distances ΔXX and ΔXY between the second designated alignment mark's motion stage coordinates (X1, Y1) and the first designated alignment mark's motion stage coordinates (X0, Y0) in the X-axis direction and the Y-axis direction of the motion stage coordinates includes: The mapping distances ΔXX and ΔXY are calculated according to the formulas ΔXX=X1-X0, ΔXY=Y1-Y0.

11. The alignment mark positioning compensation method according to claim 8, characterized in that: The step of calculating the motion stage coordinates (X2, Y2) of the third designated alignment mark of the wafer under test under the auxiliary camera comprises: Move the motion stage to (X0, Y0 + ShotSizeY), identify and locate the image of the third designated alignment mark within the field of view of the secondary camera through template matching, calculate the coordinate deviation between the image coordinates of the third designated alignment mark and the center of the field of view, and move the image of the third designated alignment mark to the center of the field of view according to the coordinate deviation, and obtain the motion stage coordinates (X2, Y2) of the third designated alignment mark (for example, alignment mark (0, 1)).

12. The alignment mark positioning compensation method according to claim 8, wherein: The step of calculating the mapping distances ΔYX, ΔYY between the third designated alignment mark's motion stage coordinates (X2, Y2) and the first designated alignment mark's motion stage coordinates (X0, Y0) in the X-axis direction and the Y-axis direction of the motion stage coordinates includes: The mapping distances ΔYX, ΔYY are calculated according to the formulas ΔYX=X2-X0, ΔYY=Y2-Y0.

13. The alignment mark positioning compensation method according to claim 4, characterized in that: The step of calculating the coordinates of any alignment mark according to the loading error and the mapping distance, and using the main camera to measure the position deviation of the arbitrary alignment mark to dynamically compensate for the coordinate calculation of the next arbitrary alignment mark includes: a. Calculate the coordinates (X, Y) of any alignment mark according to formula (1): X=x0-ΔX+N*ΔXX+M*ΔYX+offsetX Y=y0-ΔY+N*ΔXY+M*ΔYY+offsetY Formula (1) in, (X,Y): coordinates of the motion stage of any alignment mark (alignment mark (N,M)) under the main camera; (x0, y0): coordinates of the motion stage of the first specified alignment mark under the main camera; (ΔX, ΔY): The loading error of the first designated alignment mark under the secondary camera; (ΔXX, ΔXY): The mapping distance of a single alignment mark moved laterally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔXX and ΔXY between adjacent alignment marks on the left and right sides in the X-axis direction and the Y-axis direction); (ΔYX, ΔYY): The mapping distance of a single alignment mark moved longitudinally on the X-axis and Y-axis of the motion stage coordinate system under the secondary camera (i.e., the spacing ΔYX and ΔYY between the upper and lower adjacent alignment marks in the X-axis direction and the Y-axis direction); (N, M): corresponding row and column numbers of any alignment mark on the wafer under test; (offsetX, offsetY): the position offset on the X-axis and Y-axis under the main camera; b. Update the motion stage coordinates of the arbitrary alignment mark under the main camera to (FoundX, FoundY), and then update the offsetX and offsetY values. c. Repeat steps a and b to calculate the coordinates of any other alignment marks of the wafer being measured.

14. The alignment mark positioning compensation method according to claim 13, characterized in that: The step b comprises: When the coordinates of the first arbitrary alignment mark are calculated using formula (1), offsetX and offsetY are initialized to 0. After the coordinates are calculated, the motion stage is moved to the coordinates. The image of the first arbitrary alignment mark is identified and located within the field of view of the main camera by template matching, and the coordinate deviation between the image coordinates of the first arbitrary alignment mark and the center of the field of view of the main camera is calculated. The image of the first arbitrary alignment mark is moved to the center of the field of view of the main camera according to the coordinate deviation, and the motion stage coordinates (FoundX, FoundY) of the first arbitrary alignment mark under the main camera are obtained. The offsetX and offsetY values ​​are updated according to the formulas offsetX=offsetX+FoundX-X, offsetY=offsetY+FoundY-Y.

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