CN117116914A - Measurement mark and measurement method for wafer alignment - Google Patents

Measurement mark and measurement method for wafer alignment Download PDF

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Publication number
CN117116914A
CN117116914A CN202311376752.3A CN202311376752A CN117116914A CN 117116914 A CN117116914 A CN 117116914A CN 202311376752 A CN202311376752 A CN 202311376752A CN 117116914 A CN117116914 A CN 117116914A
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mark
wafer
strips
offset
level
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CN117116914B (en
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任潮群
霍志军
陈泳
崔国江
崔建敏
杨冬野
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Suzhou Xinhuilian Semiconductor Technology Co ltd
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Suzhou Xinhuilian Semiconductor Technology Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/544—Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/10—Measuring as part of the manufacturing process
    • H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2223/00—Details relating to semiconductor or other solid state devices covered by the group H01L23/00
    • H01L2223/544—Marks applied to semiconductor devices or parts
    • H01L2223/54426—Marks applied to semiconductor devices or parts for alignment

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)

Abstract

The invention discloses a measurement mark and a measurement method for wafer alignment, and relates to the technical field of semiconductors. The measurement mark includes: an X-direction measurement mark for measuring the offset of the upper wafer and the lower wafer to be aligned in the X direction, wherein the X-direction measurement mark comprises a first X-direction offset measurement mark for being arranged on the surface of the upper wafer and a second X-direction offset measurement mark for being arranged on the surface of the lower wafer; the Y-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer in the Y direction and comprises a first Y-direction offset measuring mark used for being arranged on the surface of the upper wafer and a second Y-direction offset measuring mark used for being arranged on the surface of the lower wafer; r is R z Orientation measurement mark for determining R of upper and lower wafers z A directional offset including a first R for being disposed on the upper wafer surface z Directional offset measurement indicia and second R for placement on lower wafer surface z The measurement mark is shifted. The invention can improve the alignment precision of two wafersThereby achieving high quality wafer bonding.

Description

Measurement mark and measurement method for wafer alignment
Technical Field
The invention relates to the technical field of semiconductors, in particular to a measuring mark and a measuring method for wafer alignment.
Background
With the widespread acceptance of concepts beyond moles, advanced packaging technologies for vertical interconnect applications are rapidly evolving based on heterogeneous integration. With the bump process, the TSV (through silicon via) technology is mature and perfect, and the requirements for wafer bonding technology are also increasing. The wafer bonding has the main function of combining two wafers in the vertical direction so as to realize signal interconnection between the wafers. The primary condition for achieving good interconnection of signals is to finish accurate alignment of two wafers.
At present, the wafer alignment is realized by the following methods: including face-to-face, back, infrared, and transparent alignment, etc. Meanwhile, there are various ways to evaluate and verify performance indexes of the alignment unit. The methods basically adopt visible light or infrared light sources, the marks are shot by utilizing a microscope objective, and then measurement calculation is carried out through special software to give offset data. However, the price of a measuring microscope with a measuring function is usually hundreds of thousands, and the measuring microscope is expensive and has high cost. Furthermore, the rotational offset present in the alignment cannot be represented by direct measurement, but can be given only by means of manual calculation, which is not only computationally complex but also time-consuming and labor-consuming.
Disclosure of Invention
In view of the above, the embodiments of the present application provide a measurement mark and a measurement method for wafer alignment, so as to achieve the purpose of improving the alignment accuracy of two wafers, thereby realizing high-quality wafer bonding.
The embodiment of the application provides the following technical scheme: a measurement mark for wafer alignment, comprising:
the X-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the X direction; the X-direction measuring marks comprise a first X-direction offset measuring mark used for being arranged on the surface of the upper wafer and a second X-direction offset measuring mark used for being arranged on the surface of the lower wafer;
the Y-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the Y direction; the Y-direction measuring marks comprise a first Y-direction deviation measuring mark used for being arranged on the surface of the upper wafer and a second Y-direction deviation measuring mark used for being arranged on the surface of the lower wafer;
R z a direction measurement mark for measuring R of the upper wafer and the lower wafer to be aligned z Offset of direction; the R is z The orientation measurement mark includes a first R for placement on the upper wafer surface z A direction shift measurement mark, and a second R for being disposed on the lower wafer surface z Offset measurement marks;
wherein the first X-direction offset measurement mark, the second X-direction offset measurement mark, the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by uniformly and linearly arranging and connecting a plurality of mark strips with the same width, and the first R is formed by z A direction shift measurement mark and the second R z The mark strips with the same width are arranged on corresponding circular arcs with set central angles at equal intervals and are connected with each other; the center distance between two adjacent marking strips on the first X-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second X-direction offset measurement mark, and the center distance between two adjacent marking strips on the first Y-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second Y-direction offset measurement mark; the first R z A center distance between two adjacent marking strips on the offset measurement mark and the second R z The center-to-center distance between two adjacent marker strips on the offset measurement marker is the same.
According to one embodiment of the application, the first X-direction offset measurement mark and the second X-direction offset measurement mark are respectively formed by uniformly and transversely arranging and connecting a mark strips with the same width at equal intervals, wherein a is more than or equal to 3 and is an odd number.
According to one embodiment of the present application, a mark level is set on each of the mark bars on the first X-direction shift measurement mark and the second X-direction shift measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, starting from the 0 th-level marking strip, all marking strips are sequentially defined as negative 1-level marking strips, negative 2-level marking strips, … … and negative (a-1)/2-level marking strips from right to left, and all marking strips are sequentially defined as positive 1-level marking strips, positive 2-level marking strips, … … and positive (a-1)/2-level marking strips from left to right.
According to one embodiment of the application, the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by longitudinally arranging b mark strips with the same width at equal intervals and mutually connecting, wherein b is more than or equal to 3 and is an odd number.
According to one embodiment of the present application, a mark level is set on each of the mark bars on the first Y-direction shift measurement mark and the second Y-direction shift measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, from the 0 th-level marking strip to the top, each marking strip is sequentially defined as a negative 1-level marking strip, a negative 2-level marking strip, … … and a negative (b-1)/2-level marking strip, and each marking strip is sequentially defined as a positive 1-level marking strip, a positive 2-level marking strip, … … and a positive (b-1)/2-level marking strip from top to bottom.
According to one embodiment of the application, the first R z A direction shift measurement mark and the second R z The mark strips with the same width are arranged at equal intervals on the circular arcs corresponding to the set central angles and are connected with each other; the circle center of the upper wafer or the lower wafer is the circle center of the circular arc, the radius R of the circular arc is smaller than the radii of the upper wafer and the lower wafer, and c is more than or equal to 2.
According to one embodiment of the application, the first R z A direction shift measurement mark and the second R z Setting a mark level on each of the mark strips on the offset measurement mark; wherein in the right-to-left direction, the rightmost label isThe marking bars are defined as 0 th level marking bars, from the 0 th level marking bar to the left in turn, each marking bar is defined as 1 level marking bar, 2 level marking bar, … …, (c-1) level marking bar in turn.
The application also provides a measuring method which is applied to the measuring mark for wafer alignment, and comprises the following steps:
setting a first X-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second X-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the X direction, and calculating the offset delta X of the upper wafer and the lower wafer in the X direction according to the mark grade of the mutually aligned mark strips on the first X-direction offset measurement mark and the second X-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first X-direction offset measurement mark and the center distance between two adjacent mark strips on the second X-direction offset measurement mark;
Setting a first Y-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second Y-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the Y direction, and calculating the offset delta Y of the upper wafer and the lower wafer in the Y direction according to the mark grade of the mutually aligned mark strips on the first Y-direction offset measurement mark and the second Y-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first Y-direction offset measurement mark and the center distance between two adjacent mark strips on the second Y-direction offset measurement mark;
will be a first R z An offset measurement mark is arranged on the surface of the upper wafer to be aligned, and a second R is arranged z The directional offset measurement mark is arranged on the surface of the lower wafer to be aligned, and the R of the upper wafer and the lower wafer is completed z Alignment of the directions according to R z Another R aligned to the 0 th level marker strip on the offset measurement marker z The first R is the mark level of the mark strip on the offset measurement mark z A direction shift measurement mark and the second R z Mark for measuring mark to offsetCounting the number of the bars and the degree of the set central angle, and calculating R of the upper wafer and the lower wafer z The deflection angle delta theta of the direction.
According to an embodiment of the present application, the calculation formula of the offset Δx is as follows: Δx=n 1 *（X 1 -X 2 ) Wherein n is 1 To mark the mark level of the mark strips aligned with each other in the wafer and the lower wafer in the X direction, X 1 For measuring the centre distance between two adjacent marker strips on the marker for the first X-direction offset, X 2 For measuring the centre distance between two adjacent marker strips on the marker for the second X-direction offset, X 1 、X 2 Are all greater than 0, and X 1 ≠X 2 The method comprises the steps of carrying out a first treatment on the surface of the When Deltax > 0, the upper wafer is offset leftwards relative to the lower wafer, and when Deltax < 0, the upper wafer is offset rightwards relative to the lower wafer;
the calculation formula of the offset delta y is as follows: Δy=n 2 *（Y 1 -Y 2 ) Wherein n is 2 To mark the level of the mutually aligned mark stripes in the wafer and the lower wafer in the Y direction, Y 1 For measuring the centre-to-centre distance between two adjacent marker strips on the marker for the first Y-direction offset, Y 2 For measuring the centre distance between two adjacent marker strips on the marker for the second Y-direction offset, Y 1 、Y 2 Are all greater than 0, and Y 1 ≠Y 2 The method comprises the steps of carrying out a first treatment on the surface of the When Δy > 0, it means that the upper wafer is offset upward with respect to the lower wafer, and when Δy < 0, it means that the upper wafer is offset downward with respect to the lower wafer.
According to one embodiment of the present application, the deflection angle Δθ is calculated as follows: Δθ=n 3 * x/(c-1), where n 3 To be at the first R z A direction shift measurement mark and the second R z In the direction offset measurement mark, with one of R z Another R aligned to the 0 th level marker strip on the offset measurement marker z Measuring the mark level of the mark strip on the mark to the offset; x is the degree of the set central angle, c is the first R z A direction shift measurement mark and the second R z Number of marks of the offset measurement markAn amount of;
when the 0 th level mark strip of the upper wafer and the n of the lower wafer 3 When the level mark strips are aligned, the upper wafer is anticlockwise deflected relative to the lower wafer; when the 0 th level mark of the lower wafer and the n of the upper wafer 3 The alignment of the level mark bars indicates that the upper wafer is deflected clockwise relative to the lower wafer.
Compared with the prior art, the application has the beneficial effects that: the method comprises the steps that whether an upper wafer and a lower wafer are aligned or not is verified through measurement marks, namely, the upper wafer and the lower wafer are respectively provided with measurement marks, and the offset of the upper wafer and the lower wafer in the X direction is measured through the arrangement of X-direction offset measurement marks; the Y-direction offset measurement mark is set to measure the offset of the upper wafer and the lower wafer in the Y direction; by setting R z Measuring R of upper and lower wafers by shifting measurement marks z Offset to the direction. The application uses the measuring mark to carry out contraposition to verify the performance index of the contraposition unit. After the wafer is aligned, X-direction offset measurement marks, Y-direction offset measurement marks and R are aligned under a microscope objective z Observing the offset measurement mark, directly measuring without using measurement software, and reading out offset and deflection data of the upper wafer and the lower wafer after alignment is completed; meanwhile, manual calculation is not needed, so that not only can the X, Y axial offset data be simply represented, but also R can be represented z The deflection data is directly and simply represented.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of X-direction offset measurement marks (units: mm) on a wafer according to an embodiment of the present application;
FIG. 2 is a schematic view of X-direction offset measurement marks (units: mm) on a wafer according to an embodiment of the present application;
FIG. 3 is a schematic diagram showing the alignment of the upper wafer and the lower wafer in the X direction without deviation according to the embodiment of the present application;
FIG. 4 is a schematic view of the upper wafer and the lower wafer in the left-hand direction of 1um in the X direction according to the embodiment of the present application;
FIG. 5 is a schematic view of the upper wafer and the lower wafer in the right direction of 1um in the X direction according to the embodiment of the present application;
FIG. 6 is a schematic diagram of Y-direction offset measurement marks on an upper wafer and a lower wafer according to an embodiment of the present application;
FIG. 7 is a diagram showing 3 shifts in the Y direction of the upper and lower wafers after alignment is completed according to the embodiment of the present application;
FIG. 8 is a schematic diagram of a complete measurement mark on a wafer according to an embodiment of the present application;
FIG. 9 is a schematic diagram of a complete measurement mark on a wafer according to an embodiment of the present application;
FIG. 10 is a schematic diagram of an embodiment of the present application after the upper wafer and the lower wafer are completely aligned;
FIG. 11 is a schematic diagram of an embodiment of the present application after the upper wafer and the lower wafer are aligned and misaligned;
FIG. 12 is a diagram of R on an upper wafer and a lower wafer according to an embodiment of the present application z Schematic diagram of the offset measurement mark;
FIG. 13 is a graph of R for an upper wafer versus a lower wafer in accordance with an embodiment of the present application z Schematic rotated 0.1 ° clockwise upward.
Detailed Description
Embodiments of the present application will be described in detail below with reference to the accompanying drawings.
Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict. 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.
As shown in fig. 1, an embodiment of the present invention provides a measurement mark for wafer alignment, including:
the X-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the X direction; the X-direction measuring marks comprise a first X-direction offset measuring mark used for being arranged on the surface of the upper wafer and a second X-direction offset measuring mark used for being arranged on the surface of the lower wafer;
the Y-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the Y direction; the Y-direction measuring marks comprise a first Y-direction deviation measuring mark used for being arranged on the surface of the upper wafer and a second Y-direction deviation measuring mark used for being arranged on the surface of the lower wafer;
R z a direction measurement mark for measuring R of the upper wafer and the lower wafer to be aligned z Offset of direction; the R is z The orientation measurement mark includes a first R for placement on the upper wafer surface z A direction shift measurement mark, and a second R for being disposed on the lower wafer surface z Offset measurement marks;
wherein the first X-direction offset measurement mark, the second X-direction offset measurement mark, the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by uniformly and linearly arranging and connecting a plurality of mark strips with the same width, and the first R is formed by z A direction shift measurement mark and the second R z The mark strips with the same width are arranged on corresponding circular arcs with set central angles at equal intervals and are connected with each other; the center distance between two adjacent marking strips on the first X-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second X-direction offset measurement mark, and the center distance between two adjacent marking strips on the first Y-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second Y-direction offset measurement mark; the first R z Offset toMeasuring the center distance between two adjacent marking strips on the mark and the second R z The center-to-center distance between two adjacent marker strips on the offset measurement marker is the same.
In the embodiment of the invention, whether the upper wafer and the lower wafer are aligned or not is verified by respectively arranging the measuring marks on the upper wafer and the lower wafer, and the offset of the upper wafer and the lower wafer in the X direction is measured by arranging the X-direction offset measuring marks; the Y-direction offset measurement mark is set to measure the offset of the upper wafer and the lower wafer in the Y direction; by setting R z Measuring the R of the upper and lower wafers with an offset measurement mark z Offset to the direction. The embodiment of the invention utilizes the measurement mark to carry out alignment so as to verify the performance index of the alignment unit. After the wafer pair is aligned, the X-direction offset measurement mark, the Y-direction offset measurement mark and R are aligned under a microscope objective z Observing the offset measurement mark, directly measuring without using measurement software, and reading out offset and deflection data of the upper wafer and the lower wafer after alignment is completed; meanwhile, manual calculation is not needed, so that not only can the X, Y axial offset data be simply represented, but also R can be represented z The deflection data is directly and simply represented. Wherein R is z The direction refers to deflection in the xy plane between the lower wafer and the upper wafer.
In some embodiments, the first X-direction offset measurement mark and the second X-direction offset measurement mark are respectively formed by uniformly and transversely arranging a mark strips with the same width at equal intervals and mutually connecting, wherein a is more than or equal to 3 and is an odd number, and the mark strips are rectangular or square.
In the first X-direction offset measurement mark on the upper wafer, the center distance between two adjacent mark strips is X 1 The bottom edges of all the marking strips are positioned on a first horizontal line in the X direction; in the second X-direction offset measurement mark on the lower wafer, the center distance between two adjacent mark strips is X 2 The top edges of all the marking strips are positioned on the first horizontal line.
A mark grade is set on each mark strip on the first X-direction offset measurement mark and the second X-direction offset measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, starting from the 0 th-level marking strip, all marking strips are sequentially defined as negative 1-level marking strips, negative 2-level marking strips, … … and negative (a-1)/2-level marking strips from right to left, and all marking strips are sequentially defined as positive 1-level marking strips, positive 2-level marking strips, … … and positive (a-1)/2-level marking strips from left to right.
In this embodiment, the X-direction offset measurement marks on the upper and lower wafers are X-direction mark bar groups formed by arranging a number of mark bars in a row in the lateral direction, all the mark bars in the X-direction mark bar groups are defined to make the X-direction mark bar groups act as scales to measure the X-direction offset, and different center distances are set between two adjacent mark bars in the X-direction mark bar groups of the upper and lower wafers 1 And X 2 Based on the number of stages of the mark strips aligned in the X-direction wafer and the lower wafer, offset data of the X-direction upper wafer and the X-direction lower wafer after alignment is directly read out through observation of a microscope, and different alignment precision of the X-direction upper wafer and the X-direction lower wafer can be verified through adjusting the center distance between the mark strips.
Specific examples are as follows: the measuring wafer pair includes: an upper wafer, and a lower wafer. The upper wafer includes one or N sets of measurement marks (N > 1), the measurement marks including: the first X-direction is offset from the measurement mark. The lower wafer comprises one or N groups of measurement marks (N > 1), wherein the measurement marks comprise: the second X-direction is offset from the measurement mark. The number of the measurement mark groups on the upper wafer and the lower wafer is the same, and the first X-direction offset measurement mark on the upper wafer and the second X-direction offset measurement mark on the lower wafer are matched measurement marks.
The first X-direction offset measurement mark on the upper wafer has the following characteristics:
the first X-direction offset measurement on the upper wafer is marked as an X-direction marking strip group which is formed by transversely arranging 21 marking strips, the width of each marking strip is 20um, and the center distance X between the marking strips 1 Is 30um. The bottom edges of all the marking strips are positioned on the first horizontal line in the X direction.
In the X-direction marker strip group of the upper wafer, the marker strip height at the middle is 60um, and the marker strip is defined as the 0 th level marker strip. In the X-direction offset measurement mark on the upper wafer, starting from the 0 th level mark, each mark is sequentially defined as a negative 1 level mark, a negative 2 level mark … … and a negative 10 level mark from right to left. In the X-direction offset measurement mark on the upper wafer, starting from the 0 th level mark, each mark is sequentially defined as a positive 1 level mark, a positive 2 level mark … … and a positive 10 level mark from left to right.
Referring to fig. 1, in the first X-direction offset measurement mark on the upper wafer, the negative 5-level mark bar has a height of 40um, the negative 10-level mark bar has a height of 60um, and the rest mark bars have a height of 30um, among the negative 1-level mark bar to the negative 10-level mark bar. In the first X-direction offset measurement mark on the upper wafer, the height of the positive 5-level mark strip is 40um, the height of the positive 10-level mark strip is 60um, and the heights of the rest mark strips are 30um in the positive 1-level mark strip to the positive 10-level mark strip.
The second X-direction offset measurement mark on the lower wafer has the following characteristics:
the second X-direction offset measurement on the lower wafer is marked as an X-direction marking strip group which is formed by transversely arranging 21 marking strips, the width of each marking strip is 20um, and the center distance X between the marking strips 2 Is 31um. The top edges of all the marking strips are positioned on the first horizontal line.
In the X-direction marker strip group of the lower wafer, the marker strip height at the middle is 60um, and the marker strip is defined as the 0 th level marker strip. In the second X-direction offset measurement mark on the lower wafer, starting from the 0 th level mark, each mark is sequentially defined as a negative 1 level mark, a negative 2 level mark … … and a negative 10 level mark from right to left. In the second X-direction offset measurement mark on the lower wafer, starting from the 0 th level mark, each mark is sequentially defined as a positive 1 level mark, a positive 2 level mark … … and a positive 10 level mark from left to right.
Referring to fig. 2, in the second X-direction offset measurement mark on the lower wafer, the negative 5-level mark bar has a height of 40um, the negative 10-level mark bar has a height of 60um, and the rest mark bars have a height of 30um, among the negative 1-level mark bar to the negative 10-level mark bar. In the second X-direction offset measurement mark on the lower wafer, the height of the positive 5-level mark strip is 40um, the height of the positive 10-level mark strip is 60um, and the heights of the rest mark strips are 30um in the positive 1-level mark strip to the positive 10-level mark strip.
After alignment is completed, one or only one of the first X-direction offset measurement mark strips on the upper wafer is aligned with the second X-direction offset measurement mark strip on the lower wafer.
Referring to fig. 3, when the 0 th level mark stripe of the first X-direction offset measurement mark on the upper wafer is aligned with the 0 th level mark stripe of the second X-direction offset measurement mark on the lower wafer, the alignment deviation (offset) between the upper wafer and the lower wafer in the X-direction is approximately 0um.
Referring to fig. 4, when the negative 1-level mark of the first X-direction shift measurement mark on the upper wafer is aligned with the negative 1-level mark of the second X-direction shift measurement mark on the lower wafer, the shift amount of the upper wafer to the left in the X-direction with respect to the lower wafer is 1um.
Referring to fig. 5, when the positive 1-level mark bar of the first X-direction shift measurement mark on the upper wafer is aligned with the positive 1-level mark bar of the second X-direction shift measurement mark on the lower wafer, the shift amount of the upper wafer relative to the lower wafer in the X-direction to the right is 1um.
In summary, the calculation formula of the offset Δx in the X direction after the alignment of the upper wafer and the lower wafer is completed is as follows: Δx=n 1 *（X 1 -X 2 ) Wherein n is 1 To mark the mark level of the mark strips aligned with each other in the wafer and the lower wafer in the X direction, X 1 For measuring the centre distance between two adjacent marker strips on the marker for the first X-direction offset, X 2 For measuring the centre distance between two adjacent marker strips on the marker for the second X-direction offset, X 1 、X 2 Are all greater than 0, and X 1 ≠X 2 The method comprises the steps of carrying out a first treatment on the surface of the When Δx > 0, it means that the upper wafer is shifted leftward with respect to the lower wafer, and when Δx < 0, it means that the upper wafer is shifted rightward with respect to the lower wafer.
X 1 And X 2 The larger the difference value of the (B) is, the larger the offset deltax is due to the proportional relation, and the less high the requirement on the observation precision of the microscope objective lens is；X 1 And X 2 The smaller the difference in (a) is, the smaller the offset deltax is due to the proportional relationship, and the higher the requirement on the observation accuracy of the microscope objective is.
In some embodiments, the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by longitudinally arranging b mark strips with the same width at equal intervals and connecting the two mark strips with each other, wherein b is more than or equal to 3 and is an odd number, and the mark strips are rectangular or square.
In the first Y-direction offset measurement mark on the upper wafer, the center distance between two adjacent mark strips is Y 1 The right sides of all the marking strips are positioned on a second horizontal line in the Y direction; in the second Y-direction offset measurement mark on the lower wafer, the center distance between two adjacent mark strips is Y 2 The left sides of all the marking strips are positioned on the second horizontal line.
In the Y-direction mark strip group, mark grades are set on each mark strip on the first Y-direction offset measurement mark and the second Y-direction offset measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, from the 0 th-level marking strip to the top, each marking strip is sequentially defined as a negative 1-level marking strip, a negative 2-level marking strip, … … and a negative (b-1)/2-level marking strip, and each marking strip is sequentially defined as a positive 1-level marking strip, a positive 2-level marking strip, … … and a positive (b-1)/2-level marking strip from top to bottom.
In this embodiment, the Y-direction offset measurement marks on the upper and lower wafers are all Y-direction mark bar groups formed by longitudinally and sequentially arranging b mark bars, the Y-direction mark bar groups are defined by defining all mark bars in the Y-direction mark bar groups to act as scales to measure the Y-direction offset, and different center distances are set between two adjacent mark bars in the Y-direction mark bar groups of the upper and lower wafers to be Y 1 And Y 2 Based on the number of the stages of the mark strips aligned in the Y-direction wafer and the lower wafer, the offset data of the upper wafer and the lower wafer in the Y-direction after the alignment is directly read out through the observation of a microscope, and the center distance between the mark strips can be adjusted to verify that the upper wafer and the lower wafer are in the Y-directionDifferent alignment accuracy of (a).
Specific examples are as follows: the upper wafer includes one or N sets of measurement marks (N > 1), and the measurement marks further include: the first Y-direction is offset from the measurement indicia. The lower wafer includes one or N sets of measurement marks (N > 1), and the measurement marks further include: the second Y-direction is offset from the measurement indicia. The number of the measurement mark groups on the upper wafer and the lower wafer is the same, and the first Y-direction deviation measurement mark on the upper wafer and the second Y-direction deviation measurement mark on the lower wafer are matched measurement marks.
Referring to fig. 6, the first Y-direction offset measurement mark on the upper wafer has the following characteristics:
the first Y-direction offset measurement on the upper wafer is marked as a Y-direction marking strip group which is longitudinally arranged in a row by 21 marking strips, the width of each marking strip is 20um, and the center distance Y between the marking strips 1 Is 30um. The right sides of all the marker strips are on the second horizontal line in the Y direction.
In the Y-direction marker strip group of the upper wafer, the length of the marker strip at the middle is 60um, and the marker strip is defined as the 0 th-level marker strip. In the first Y-direction offset measurement mark on the upper wafer, starting from the 0 th level mark stripe, each mark stripe is sequentially defined as a negative 1 level mark stripe, a negative 2 level mark stripe … … and a negative 10 level mark stripe from bottom to top. In the first Y-direction offset measurement mark on the upper wafer, starting from the 0 th level mark, each mark is sequentially defined as a positive 1 level mark, a positive 2 level mark … … and a positive 10 level mark from top to bottom.
In the first Y-direction offset measurement mark on the upper wafer, the length of the negative 5-level mark strip is 40um, the length of the negative 10-level mark strip is 60um, and the lengths of the rest mark strips are 30um in the negative 1-level mark strip to the negative 10-level mark strip. In the first Y-direction offset measurement mark on the upper wafer, the length of the positive 5-level mark strip is 40um, the length of the positive 10-level mark strip is 60um, and the lengths of the rest mark strips are 30um in the positive 1-level mark strip to the positive 10-level mark strip.
Referring to fig. 6, the characteristics of the second Y-direction offset measurement mark on the lower wafer are as follows:
the second Y-direction offset measurement on the lower wafer is marked by 21 marksY-direction marking strip groups with strips longitudinally arranged in a row, each marking strip has a width of 20um, and the center distance Y between the marking strips 2 Is 31um. The left sides of all the marker strips are on the second horizontal line.
In the Y-direction marker strip group of the lower wafer, the length of the marker strip at the middle is 60um, and the marker strip is defined as the 0 th-level marker strip. In the second Y-direction offset measurement mark on the lower wafer, starting from the 0 th level mark strip, each mark strip is sequentially defined as a negative 1 level mark strip, a negative 2 level mark strip … … and a negative 10 level mark strip from bottom to top. In the second Y-direction offset measurement mark on the lower wafer, starting from the 0 th level mark, each mark is sequentially defined as a positive 1 level mark, a positive 2 level mark … … and a positive 10 level mark from top to bottom.
In the second Y-direction offset measurement mark on the lower wafer, the length of the negative 5-level mark strip is 40um, the length of the negative 10-level mark strip is 60um, and the lengths of the rest mark strips are 30um in the negative 1-level mark strip to the negative 10-level mark strip. In the second Y-direction offset measurement mark on the lower wafer, in the positive 1-level mark strip to the positive 10-level mark strip, the length of the positive 5-level mark strip is 40um, the length of the positive 10-level mark strip is 60um, and the lengths of the rest mark strips are 30um.
After alignment is completed, one or only one of the first Y-direction offset measurement mark stripes on the upper wafer is aligned with the second Y-direction offset measurement mark stripe on the lower wafer.
Referring to fig. 7, when the 0 th level mark stripe of the first Y-direction shift measurement mark on the upper wafer is aligned with the 0 th level mark stripe of the second Y-direction shift measurement mark on the lower wafer, it indicates that the alignment deviation (shift amount) of the upper wafer and the lower wafer in the Y-direction is close to 0um.
Referring to fig. 7, when the negative 1 level mark bar of the first Y-direction shift measurement mark on the upper wafer is aligned with the negative 1 level mark bar of the second Y-direction shift measurement mark on the lower wafer, the shift amount of the upper wafer in the Y-direction relative to the lower wafer is 1um.
Referring to fig. 7, when the positive 1-level mark bar of the first Y-direction shift measurement mark on the upper wafer is aligned with the positive 1-level mark bar of the second Y-direction shift measurement mark on the lower wafer, the shift amount of the upper wafer in the Y-direction downward direction relative to the lower wafer is 1um.
In summary, the calculation formula of the offset Δy is as follows: Δy=n 2 *（Y 1 -Y 2 ) Wherein n is 2 To mark the level of the mutually aligned mark stripes in the wafer and the lower wafer in the Y direction, Y 1 For measuring the centre-to-centre distance between two adjacent marker strips on the marker for the first Y-direction offset, Y 2 For measuring the centre distance between two adjacent marker strips on the marker for the second Y-direction offset, Y 1 、Y 2 Are all greater than 0, and Y 1 ≠Y 2 The method comprises the steps of carrying out a first treatment on the surface of the When Δy > 0, it means that the upper wafer is offset upward with respect to the lower wafer, and when Δy < 0, it means that the upper wafer is offset downward with respect to the lower wafer.
Y 1 And Y 2 The larger the difference value of the (a) is, the larger the offset delta y is due to the proportional relation, and the requirement on the observation precision of the microscope objective is not high; y is Y 1 And Y 2 The smaller the difference in (a) is, the smaller the offset deltay is due to the proportional relationship, and the higher the requirement on the observation accuracy of the microscope objective is.
In some embodiments, the first R z A direction shift measurement mark and the second R z The mark strips with the same width are arranged at equal intervals on the circular arcs corresponding to the set central angles and are connected with each other; the circle center of the upper wafer or the lower wafer is the circle center of the circular arc, the radius R of the circular arc is smaller than the radii of the upper wafer and the lower wafer, and c is more than or equal to 2.
The radius R of the arc is smaller than the radius of the upper and lower wafers because if it is greater than or equal to the radius of the wafers, the marker strip will not fall on the wafers, but the closer R is to the wafer radius, the better the observation.
First R on the upper wafer z In the offset measurement mark, the bottom lines of all mark strips are on an arc; second R on the lower wafer z In the offset measurement mark, the top lines of all mark strips are on the circular arc.
In this embodiment, the first R z A direction shift measurement mark and the second R z Setting a mark level on each of the mark strips on the offset measurement mark; wherein, in the right-to-left direction, the rightmost marker strip is defined as a 0 th-level marker strip, and from the 0 th-level marker strip to the left in turn, each marker strip is defined as a 1-level marker strip, a 2-level marker strip, and a … … (c-1) level marker strip in turn.
In the present embodiment, R on the upper wafer and the lower wafer z The measurement marks of the axial offset are all formed by c mark strips, R are arranged at equal intervals on an arc with radius R and central angle x z To the marker strip group by R z Defining all marker strips in the marker strip group so that R z Role of acting as a ruler to the marker strip set measures R z The amount of deflection in the direction, i.e., the angle of deflection clockwise and counterclockwise; based on R z The number of the marking strips aligned in the upper wafer and the lower wafer is directly read out by the observation of a microscope, and the upper wafer and the lower wafer are positioned in R z The deflection angle of the direction can also verify different alignment precision of the upper wafer and the lower wafer in the Y direction by adjusting the number and the central angle of the marking strips.
Wherein, the rectangular or square mark strips are arranged to facilitate the observation of the offset of the upper wafer and the lower wafer in the X direction and the Y direction and the R direction respectively by a microscope z Amount of deflection in the direction.
Specific examples are as follows: the upper wafer includes one or N sets of measurement marks (N > 1), and the measurement marks further include: first R z The measurement mark is shifted. The lower wafer includes one or N sets of measurement marks (N > 1), and the measurement marks further include: second R z The measurement mark is shifted. Wherein the number of the measurement mark groups on the upper wafer is the same as that of the measurement mark groups on the lower wafer, and the first R on the upper wafer z Offset measurement mark and second R on lower wafer z The offset measurement mark is a matched measurement mark.
First R on upper wafer z The characteristics of the shift-to-shift measurement marks are as follows:
first R on upper wafer z The directional offset measurement mark consists of 101 mark strips, and the circle center of the above wafer is an arcR (R=145 mm in the present embodiment) is a radius, and R is arranged at equal intervals on an arc having a central angle of 1 DEG z To the set of marker strips, each marker strip has a width of 20um, and the bottom lines of all marker strips are on an arc.
R of upper wafer z The rightmost marker strip, defined as the 0 th level marker strip, has a height of 60um into the marker strip set. First R on upper wafer z In the offset measurement mark, from the 0 th level mark bar to the left, each mark bar is defined as a 1 level mark bar, a 2 level mark bar … … level mark bar in order.
First R on upper wafer z In the offset measurement marks, 5 th (2 n-1), n [ E [1, 10 ] in the 1 st level mark strip to the 100 th level mark strip]The height of the level mark strip is 40um, 10 x n, n E [1, 10]The height of the level marking strips is 60um, and the heights of the rest marking strips are 30um, wherein n is an integer used for calculation.
Second R on lower wafer z The characteristics of the shift-to-shift measurement marks are as follows:
second R on lower wafer z The direction offset measurement mark consists of 101 mark strips, wherein the circle center of the following wafer is the circle center of an arc, R (R=145 mm in the embodiment) is the radius, and R is arranged at equal intervals on the arc with the circle center angle of 1 DEG z To the marker strip group, the width of each marker strip is 20um, and the top lines of all marker strips are on the circular arc.
R of lower wafer z The rightmost marker strip, defined as the 0 th level marker strip, has a height of 60um into the marker strip set. Second R on lower wafer z In the offset measurement mark, from the 0 th level mark bar to the left, each mark bar is defined as a 1 level mark bar, a 2 level mark bar … … level mark bar in order.
Second R on lower wafer z In the offset measurement marks, 5 th (2 n-1), n [ E [1, 10 ] in the 1 st level mark strip to the 100 th level mark strip]The height of the level mark strip is 40um, 10 th c, n E [1, 10 ]]The height of the level marking strips is 60um, and the heights of the rest marking strips are 30um, wherein n is an integer used for calculation.
With reference to FIGS. 12 and 13, alignment is completedThen, all the first R on the upper wafer z Marker strip of the offset measurement marker and all second R on the lower wafer z When the mark strips of the offset measurement marks are aligned, the upper wafer and the lower wafer are represented as R z The upward alignment deviation is approximately 0 °.
When the first R on the upper wafer z Level 1 marker strip of offset measurement marker and second R on lower wafer z When the 0 th level mark strip of the offset measurement mark is aligned, the upper wafer is relative to the lower wafer in R z Rotated up clockwise by 0.01 deg..
When the first R on the upper wafer z Level 0 marker strip of the offset measurement marker and second R on the lower wafer z When the 1-level mark strips of the offset measurement marks are aligned, the alignment of the 1-level mark strips indicates that the upper wafer is opposite to the lower wafer in R z Rotated up and counter-clockwise by 0.01.
To sum up, after the alignment of the upper wafer and the lower wafer is completed, R is z The calculation formula of the deflection angle delta theta is as follows: Δθ=n 3 * x/(c-1), where n 3 To be at the first R z A direction shift measurement mark and the second R z In the direction offset measurement mark, with one of R z Another R aligned to the 0 th level marker strip on the offset measurement marker z Measuring the mark level of the mark strip on the mark to the offset; x is the degree of the set central angle, c is the first R z A direction shift measurement mark and the second R z The number of marker strips to offset the measurement marker; when the 0 th level mark strip of the upper wafer and the n of the lower wafer 3 When the level mark strips are aligned, the upper wafer is anticlockwise deflected relative to the lower wafer; when the 0 th level mark of the lower wafer and the n of the upper wafer 3 The alignment of the level mark bars indicates that the upper wafer is deflected clockwise relative to the lower wafer.
When the central angle x is fixed, the larger the number c of the marker strips is, the smaller the deflection angle delta theta is, and the higher the requirement on the observation precision of the microscope objective lens is for the convenience of measurement; when the central angle x is fixed, the smaller the number c of the marker strips is, the larger the deflection angle delta theta is, and the requirement on the observation precision of the microscope objective lens is not high.
When the number c of the marking strips is fixed, the larger the central angle x is, the larger the deflection angle delta theta is, and the requirement on the observation precision of the microscope objective lens is not high due to the proportional relation; when the number c of the marker strips is fixed, the smaller the central angle x is, the smaller the deflection angle delta theta is, and the higher the requirement on the observation precision of the microscope objective lens is for the convenience of measurement.
The embodiment also provides a measuring method, which is applied to the measuring mark and can be applied to other scenes for verifying alignment accuracy.
The measuring method of the embodiment of the invention comprises the following steps:
setting a first X-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second X-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the X direction, and calculating the offset delta X of the upper wafer and the lower wafer in the X direction according to the mark grade of the mutually aligned mark strips on the first X-direction offset measurement mark and the second X-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first X-direction offset measurement mark and the center distance between two adjacent mark strips on the second X-direction offset measurement mark;
setting a first Y-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second Y-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the Y direction, and calculating the offset delta Y of the upper wafer and the lower wafer in the Y direction according to the mark grade of the mutually aligned mark strips on the first Y-direction offset measurement mark and the second Y-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first Y-direction offset measurement mark and the center distance between two adjacent mark strips on the second Y-direction offset measurement mark;
Will be a first R z An offset measurement mark is arranged on the surface of the upper wafer to be aligned, and a second R is arranged z The directional offset measurement mark is arranged atThe surface of the lower wafer to be aligned is completed in R z Alignment of the directions according to R z Another R aligned to the 0 th level marker strip on the offset measurement marker z The first R is the mark level of the mark strip on the offset measurement mark z A direction shift measurement mark and the second R z Calculating R of the upper wafer and the lower wafer according to the number of the mark strips of the offset measurement mark and the degree of the set central angle z The deflection angle delta theta of the direction.
Verifying whether the upper wafer and the lower wafer are aligned by respectively setting measurement marks on the upper wafer and the lower wafer, and measuring the offset of the upper wafer and the lower wafer in the X direction by setting X-direction offset measurement marks; the Y-direction offset measurement mark is set to measure the offset of the upper wafer and the lower wafer in the Y direction; by setting R z Measuring R of upper and lower wafers by shifting measurement marks z Offset to the direction. The method utilizes the measurement marks to carry out alignment so as to verify the performance index of the alignment unit. After wafer alignment is completed, X-direction offset measurement marks, Y-direction offset measurement marks and R are aligned under a microscope objective z Observing the offset measurement mark, directly measuring without using measurement software, and reading out offset and deflection data of the upper wafer and the lower wafer after alignment is completed; meanwhile, manual calculation is not needed, so that not only can the X, Y axial offset data be simply represented, but also R can be represented z The deflection data is directly and simply represented.
In this embodiment of the measurement method, the calculation formula of the offset Δx is as follows: Δx=n 1 *（X 1 -X 2 ) Wherein n is 1 To mark the mark level of the mark strips aligned with each other in the wafer and the lower wafer in the X direction, X 1 For measuring the centre distance between two adjacent marker strips on the marker for the first X-direction offset, X 2 For measuring the centre distance between two adjacent marker strips on the marker for the second X-direction offset, X 1 、X 2 Are all greater than 0, and X 1 ≠X 2 The method comprises the steps of carrying out a first treatment on the surface of the When deltax > 0, meaning that the upper wafer is offset to the left relative to the lower wafer, when deltax < 0,indicating that the upper wafer is offset to the right relative to the lower wafer;
the calculation formula of the offset delta y is as follows: Δy=n 2 *（Y 1 -Y 2 ) Wherein n is 2 To mark the level of the mutually aligned mark stripes in the wafer and the lower wafer in the Y direction, Y 1 For measuring the centre-to-centre distance between two adjacent marker strips on the marker for the first Y-direction offset, Y 2 For measuring the centre distance between two adjacent marker strips on the marker for the second Y-direction offset, Y 1 、Y 2 Are all greater than 0, and Y 1 ≠Y 2 The method comprises the steps of carrying out a first treatment on the surface of the When Δy > 0, it means that the upper wafer is offset upward with respect to the lower wafer, and when Δy < 0, it means that the upper wafer is offset downward with respect to the lower wafer.
The deflection angle delta theta is calculated as follows: Δθ=n 3 * x/(c-1), where n 3 To be at the first R z A direction shift measurement mark and the second R z In the direction offset measurement mark, with one of R z Another R aligned to the 0 th level marker strip on the offset measurement marker z Measuring the mark level of the mark strip on the mark to the offset; x is the degree of the set central angle, c is the first R z A direction shift measurement mark and the second R z The number of marker strips to offset the measurement marker; when the 0 th level mark strip of the upper wafer and the n of the lower wafer 3 When the level mark strips are aligned, the upper wafer is anticlockwise deflected relative to the lower wafer; when the 0 th level mark of the lower wafer and the n of the upper wafer 3 The alignment of the level mark bars indicates that the upper wafer is deflected clockwise relative to the lower wafer.
In some embodiments, the marker strip is rectangular or square in shape.
In the description of the above-described embodiments of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present invention, and the specific meaning of the above-described terms in the present invention will be understood to those of ordinary skill in the art in a specific case.
The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the scope of the present application should be included in the present application. Therefore, the protection scope of the application is subject to the protection scope of the claims.

Claims (10)

1. A measurement tag for wafer alignment, comprising:
the X-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the X direction; the X-direction measuring marks comprise a first X-direction offset measuring mark used for being arranged on the surface of the upper wafer and a second X-direction offset measuring mark used for being arranged on the surface of the lower wafer;
the Y-direction measuring mark is used for measuring the offset of the upper wafer and the lower wafer to be aligned in the Y direction; the Y-direction measuring marks comprise a first Y-direction deviation measuring mark used for being arranged on the surface of the upper wafer and a second Y-direction deviation measuring mark used for being arranged on the surface of the lower wafer;
R z a direction measurement mark for measuring R of the upper wafer and the lower wafer to be aligned z Offset of direction; the R is z The orientation measurement mark includes a first R for placement on the upper wafer surface z A direction shift measurement mark, and a second R for being disposed on the lower wafer surface z Offset measurement marks;
wherein the first X-direction offset measurement mark, the second X-direction offset measurement mark, the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by uniformly and linearly arranging and connecting a plurality of mark strips with the same width, and the first R is formed by z A direction shift measurement mark and the second R z The mark marks of the offset measurement are respectively set by a plurality of mark strips with the same widthThe corresponding circular arcs of the central angles are arranged at equal intervals and are connected with each other; the center distance between two adjacent marking strips on the first X-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second X-direction offset measurement mark, and the center distance between two adjacent marking strips on the first Y-direction offset measurement mark is different from the center distance between two adjacent marking strips on the second Y-direction offset measurement mark; the first R z A center distance between two adjacent marking strips on the offset measurement mark and the second R z The center-to-center distance between two adjacent marker strips on the offset measurement marker is the same.
2. The measurement mark for wafer alignment according to claim 1, wherein: the first X-direction offset measurement mark and the second X-direction offset measurement mark are respectively formed by uniformly and transversely arranging a mark strips with the same width at equal intervals and mutually connecting, wherein a is more than or equal to 3 and is an odd number.
3. The measurement mark for wafer alignment according to claim 2, wherein: a mark grade is set on each mark strip on the first X-direction offset measurement mark and the second X-direction offset measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, starting from the 0 th-level marking strip, all marking strips are sequentially defined as negative 1-level marking strips, negative 2-level marking strips, … … and negative (a-1)/2-level marking strips from right to left, and all marking strips are sequentially defined as positive 1-level marking strips, positive 2-level marking strips, … … and positive (a-1)/2-level marking strips from left to right.
4. The measurement mark for wafer alignment according to claim 1, wherein: the first Y-direction offset measurement mark and the second Y-direction offset measurement mark are respectively formed by longitudinally arranging b mark strips with the same width at equal intervals and mutually connecting, wherein b is more than or equal to 3 and is an odd number.
5. The measurement mark for wafer alignment of claim 4, wherein: a mark grade is set on each mark strip on the first Y-direction offset measurement mark and the second Y-direction offset measurement mark; the marking strips positioned at the middle are defined as 0 th-level marking strips, from the 0 th-level marking strip to the top, each marking strip is sequentially defined as a negative 1-level marking strip, a negative 2-level marking strip, … … and a negative (b-1)/2-level marking strip, and each marking strip is sequentially defined as a positive 1-level marking strip, a positive 2-level marking strip, … … and a positive (b-1)/2-level marking strip from top to bottom.
6. The measurement mark for wafer alignment according to claim 1, wherein: the first R z A direction shift measurement mark and the second R z The mark strips with the same width are arranged at equal intervals on the circular arcs corresponding to the set central angles and are connected with each other; the circle center of the upper wafer or the lower wafer is the circle center of the circular arc, the radius R of the circular arc is smaller than the radii of the upper wafer and the lower wafer, and c is more than or equal to 2.
7. The measurement mark for wafer alignment of claim 6, wherein: the first R z A direction shift measurement mark and the second R z Setting a mark level on each of the mark strips on the offset measurement mark; wherein, in the right-to-left direction, the rightmost marker strip is defined as a 0 th-level marker strip, and from the 0 th-level marker strip to the left in turn, each marker strip is defined as a 1-level marker strip, a 2-level marker strip, and a … … (c-1) level marker strip in turn.
8. A measurement method applied to the measurement mark for wafer alignment according to any one of claims 1 to 7, characterized by comprising:
setting a first X-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second X-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the X direction, and calculating the offset delta X of the upper wafer and the lower wafer in the X direction according to the mark grade of the mutually aligned mark strips on the first X-direction offset measurement mark and the second X-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first X-direction offset measurement mark and the center distance between two adjacent mark strips on the second X-direction offset measurement mark;
Setting a first Y-direction offset measurement mark on the surface of an upper wafer to be aligned, setting a second Y-direction offset measurement mark on the surface of a lower wafer to be aligned, completing the alignment of the upper wafer and the lower wafer in the Y direction, and calculating the offset delta Y of the upper wafer and the lower wafer in the Y direction according to the mark grade of the mutually aligned mark strips on the first Y-direction offset measurement mark and the second Y-direction offset measurement mark, and the difference value of the center distance between two adjacent mark strips on the first Y-direction offset measurement mark and the center distance between two adjacent mark strips on the second Y-direction offset measurement mark;
will be a first R z An offset measurement mark is arranged on the surface of the upper wafer to be aligned, and a second R is arranged z The directional offset measurement mark is arranged on the surface of the lower wafer to be aligned, and the R of the upper wafer and the lower wafer is completed z Alignment of the directions according to R z Another R aligned to the 0 th level marker strip on the offset measurement marker z The first R is the mark level of the mark strip on the offset measurement mark z A direction shift measurement mark and the second R z Calculating R of the upper wafer and the lower wafer according to the number of the mark strips of the offset measurement mark and the degree of the set central angle z The deflection angle delta theta of the direction.
9. The measurement method according to claim 8, wherein:
the calculation formula of the offset Δx is as follows: Δx=n 1 *（X 1 -X 2 ) Wherein n is 1 For marking strips aligned with each other in the X-direction and in the lower waferMarking grade, X 1 For measuring the centre distance between two adjacent marker strips on the marker for the first X-direction offset, X 2 For measuring the centre distance between two adjacent marker strips on the marker for the second X-direction offset, X 1 、X 2 Are all greater than 0, and X 1 ≠X 2 The method comprises the steps of carrying out a first treatment on the surface of the When Deltax > 0, the upper wafer is offset leftwards relative to the lower wafer, and when Deltax < 0, the upper wafer is offset rightwards relative to the lower wafer;
the calculation formula of the offset delta y is as follows: Δy=n 2 *（Y 1 -Y 2 ) Wherein n is 2 To mark the level of the mutually aligned mark stripes in the wafer and the lower wafer in the Y direction, Y 1 For measuring the centre-to-centre distance between two adjacent marker strips on the marker for the first Y-direction offset, Y 2 For measuring the centre distance between two adjacent marker strips on the marker for the second Y-direction offset, Y 1 、Y 2 Are all greater than 0, and Y 1 ≠Y 2 The method comprises the steps of carrying out a first treatment on the surface of the When Δy > 0, it means that the upper wafer is offset upward with respect to the lower wafer, and when Δy < 0, it means that the upper wafer is offset downward with respect to the lower wafer.
10. The measurement method according to claim 8, wherein:
the deflection angle delta theta is calculated as follows: Δθ=n 3 * x/(c-1), where n 3 To be at the first R z A direction shift measurement mark and the second R z In the direction offset measurement mark, with one of R z Another R aligned to the 0 th level marker strip on the offset measurement marker z Measuring the mark level of the mark strip on the mark to the offset; x is the degree of the set central angle, c is the first R z A direction shift measurement mark and the second R z The number of marker strips to offset the measurement marker;
when the 0 th level mark strip of the upper wafer and the n of the lower wafer 3 When the level mark strips are aligned, the upper wafer is anticlockwise deflected relative to the lower wafer; when the 0 th level mark of the lower wafer and the n of the upper wafer 3 When the level mark strips are aligned, the upper crystal is representedThe circle is deflected clockwise relative to the lower wafer.
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