Method for obtaining surface topography of wafer

Abstract

This invention provides a method for acquiring the surface morphology of a wafer, comprising: acquiring at least three interference fringe patterns of the wafer; dividing the wafer to obtain multiple partitions on the wafer; processing the at least three interference fringe patterns to obtain the vibrational phase shift of each partition, and obtaining a phase distribution map of each partition based on the vibrational phase shift; stitching the phase distribution maps of each partition to obtain a phase distribution map of the wafer; and converting the phase distribution map of the wafer into a height distribution map for describing the surface morphology. This invention can reduce the impact of environmental vibration on the accuracy of wafer surface morphology measurement results.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a method for obtaining the surface morphology of a wafer. Background Technology

[0002] Currently, existing technologies disclose methods for interferometric measurement of wafer surface morphology. Taking wafer morphology measurement using a dual Fizeau interferometer as an example, a cavity is formed between reference mirrors on the left and right sides along the horizontal direction. The wafer edge is fixed by a wafer clamping mechanism, and the wafer is placed vertically between the cavities. The front and back surface morphologies of the wafer are measured by the Fizeau interferometers on both sides, which can effectively reduce wafer deformation caused by gravity.

[0003] When using an interferometer to measure the morphology of a wafer, environmental vibrations can easily cause the phase shift to deviate from the preset phase shift step size. Therefore, the interferometer needs to be used with a vibration damping platform to reduce the impact of environmental vibrations, such as ground vibrations, on the morphology measurement. These environmental vibrations include air disturbances, ground vibrations, and environmental noise. However, when the interferometer operates in an industrial environment with air disturbances and / or environmental noise, the above measures cannot guarantee the accuracy of the interferometric fringe pattern acquisition, affecting the precision of the morphology measurement. Furthermore, the vibrations of traditional optical components under test, such as plane mirrors, are low-order vibrations, i.e., translation and tilting of rigid bodies. However, when measuring the morphology of a wafer, there are also flexible vibrations of the wafer itself caused by environmental vibrations. These flexible vibrations typically include higher-order vibrations. When the wafer exhibits higher-order vibrations, the applicability of existing surface morphology measurement methods is poor, affecting the accuracy of the measurement results. These higher-order vibrations are greater than or equal to two orders.

[0004] Therefore, it is necessary to provide a method for obtaining the surface morphology of a wafer. Summary of the Invention

[0005] This invention provides a method for obtaining the surface morphology of a wafer, in order to solve the technical problem that the accuracy of the morphology measurement results is low due to environmental vibration when measuring the morphology of the wafer surface in the prior art.

[0006] This invention provides a method for obtaining the surface morphology of a wafer, comprising:

[0007] Collect at least three interference fringe patterns from the wafer;

[0008] The wafer is divided to obtain multiple partitions on the wafer;

[0009] At least three of the aforementioned interference fringe patterns are processed to obtain the vibration phase shift of each partition, and the phase distribution pattern of each partition is obtained based on the vibration phase shift.

[0010] The phase distribution maps of each partition are stitched together to obtain the phase distribution map of the wafer;

[0011] The phase distribution map of the wafer is converted into a height distribution map to describe the surface morphology.

[0012] Furthermore, the process of dividing the wafer includes:

[0013] The mode shape distribution of the wafer is obtained, and the wafer is divided according to the mode shape distribution.

[0014] Furthermore, the wafer is provided with at least three support points, which are clamping points or supporting points; the division of the wafer includes dividing the wafer by connecting adjacent support points.

[0015] Furthermore, the process of dividing the wafer includes:

[0016] The wafer is divided into multiple concentric sector regions based on its center; or it is divided into a circular region and at least one annular region located around the circular region, the circular region and the annular region being concentric with respect to the center.

[0017] Furthermore, there is no overlapping area between any pair of adjacent partitions, or there is at least one pair of adjacent partitions with overlapping areas.

[0018] Furthermore, when stitching together adjacent partitions with the overlapping region, the phase data of the overlapping region in one of the partitions is used as the phase data of the overlapping region, or the average value of the phase data of the overlapping region in the partitions is used as the phase data of the overlapping region.

[0019] Furthermore, after obtaining the phase distribution map of the wafer, the process further includes:

[0020] The light intensity residual is obtained by calculating the difference between the actual light intensity value and the theoretical light intensity value at the corresponding position in the interference fringe pattern.

[0021] The light intensity residual is compared with a preset threshold. When the light intensity residual is greater than or equal to the preset threshold, the wafer is re-divided, and the vibration phase shift and phase distribution map of each partition after the wafer is re-divided are obtained.

[0022] The phase distribution maps of the re-divided partitions are stitched together to obtain the phase distribution map of the wafer.

[0023] Furthermore, the re-division of the wafer includes:

[0024] Obtain the residual contribution value corresponding to each partition, and divide the partition corresponding to the maximum value of the residual contribution value according to the mode distribution of the partition corresponding to the maximum value of the residual contribution value.

[0025] Further, the residual contribution value corresponding to each partition is obtained, including:

[0026] The average value of the light intensity residual corresponding to each partition is obtained, and the residual contribution of each partition is obtained based on the average value. The residual contribution is proportional to the average value.

[0027] Furthermore, the re-division of the wafer includes:

[0028] The wafer may be redivided by changing the size of any one or more of the sector regions, or by changing the size of any one or more of the circular and / or annular regions.

[0029] In this embodiment of the invention, the wafer is partitioned, and the vibrational phase shift of each partition is obtained. The vibrational phase shift obtained for each partition can more accurately describe the influence of environmental vibration on that partition, making the phase distribution map of each partition more accurate. This reduces the impact of environmental vibration on the accuracy of wafer surface morphology measurement results and improves the accuracy of wafer morphology measurement results. Attached Figure Description

[0030] Figure 1 A flowchart illustrating a method for obtaining the surface morphology of a wafer, as provided in an embodiment of the present invention;

[0031] Figure 2(a) is a schematic diagram of partitioning a wafer according to the mode shape distribution provided in an embodiment of the present invention;

[0032] Figure 2(b) is a schematic diagram of a wafer clamping mechanism provided in an embodiment of the present invention;

[0033] Figure 2(c) is a schematic diagram of the mode distribution on a wafer obtained after performing mode analysis on the wafer according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram illustrating how to partition a wafer based on its center point, as provided in an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram illustrating another method of partitioning a wafer based on its center point, as provided in an embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of this application are described below with reference to the accompanying drawings. In the description of the embodiments of this application, the terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to limit the application. As used in the specification and appended claims of this application, the singular expressions "a," "the," "the," "the," and "this" are intended to also include expressions such as "one or more," unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of this application, "at least one" and "one or more" refer to one or more (including two). The term "and / or" is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship.

[0037] References to "one embodiment" or "some embodiments" as used in this specification mean that one or more embodiments of this application include a specific feature, structure, or distribution described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including, but not limited to," unless otherwise specifically emphasized. The term "connection" includes direct connections and indirect connections, unless otherwise stated. "First" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0038] In the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0039] This invention provides a method for obtaining the surface morphology of a wafer, in order to solve the technical problem that the accuracy of the morphology measurement results is low due to environmental vibration when measuring the morphology of the wafer surface in the prior art.

[0040] This invention provides a method for obtaining the surface morphology of a wafer, the process of which is as follows: Figure 1 As shown, it includes:

[0041] S1. Collect at least three interference fringe patterns from the wafer;

[0042] S2. Divide the wafer to obtain multiple (at least two) partitions on the wafer;

[0043] S3. Process at least three of the aforementioned interference fringe patterns to obtain the vibration phase shift of each partition, and obtain the phase distribution map of each partition based on the vibration phase shift.

[0044] S4. The phase distribution maps of each partition are stitched together to obtain the phase distribution map of the wafer;

[0045] S5. Convert the phase distribution map of the wafer into a height distribution map to describe the surface morphology.

[0046] The execution order of steps S1 and S2 is not limited. Step S1 can be executed first, followed by step S2, or both steps S1 and S2 can be executed simultaneously, or step S2 can be executed first, followed by step S1.

[0047] In this embodiment, environmental vibrations will cause phase shift errors, also known as vibration phase shift. Based on this, the light intensity of the interference fringe pattern satisfies the following formula:

[0048] I = A + V * Cos(Φ + ωt + Δ)

[0049] Where I is the light intensity of the interference fringe pattern, A is the background light intensity, V is the modulation degree, Φ is the phase to be solved, Δ is the vibration phase shift caused by environmental vibration, ω is the preset phase shift angular frequency, and t is the fringe sampling time.

[0050] In step S3 of this embodiment, for any partition, the vibration phase shift Δ of the partition is obtained by using a phase shift algorithm based on at least three interference fringe patterns corresponding to the partition. The phase shift algorithm is, for example, a Fourier transform algorithm. Then, the phase Φ of each partition is obtained based on the vibration phase shift Δ, that is, the phase distribution map of each partition is obtained.

[0051] In view of the poor anti-interference ability of traditional morphology measurement methods against the flexible vibration of the wafer itself, this invention proposes a method for obtaining the surface morphology of a wafer. By dividing the wafer into sections, the phase distribution map of each section is obtained, and finally the phase distribution maps corresponding to each section are stitched together to obtain the phase distribution map corresponding to the entire wafer, thereby restoring the surface morphology of the wafer.

[0052] Compared with existing morphology measurement methods, the embodiments of the present invention divide the wafer into sections and obtain the vibration phase shift of each section. The vibration phase shift obtained for each section can more accurately describe the influence of environmental vibration on that section, making the phase distribution map of each section more accurate. This reduces the impact of environmental vibration on the accuracy of the wafer surface morphology measurement results and improves the accuracy of the wafer morphology measurement results.

[0053] In some embodiments, acquiring at least three interference fringe patterns of the wafer includes: acquiring at least three interference fringe patterns of the wafer using a CCD camera at a preset phase-shift step size. Specifically, at least three interference fringe patterns are acquired using a CCD camera through wavelength tuning or mechanical phase shifting at a preset phase-shift step size. For example, taking the acquisition of three interference fringe patterns as an example, first, one interference fringe pattern is acquired, then phase-shifted according to the phase-shift step size, then another interference fringe pattern is acquired after phase shifting, phase-shifted according to the phase-shift step size, and finally, another interference fringe pattern is acquired.

[0054] Exemplarily, in the step of acquiring at least three interference fringe patterns of the wafer, a single-sided or double-sided interferometer can be used, and the type of interferometer is not limited. In some embodiments, when a double-sided interferometer is used to measure the wafer surface morphology, the surface morphology includes the front surface morphology and the back surface morphology of the wafer; when a single-sided interferometer is used to measure the wafer morphology, the surface morphology includes the front surface morphology of the wafer. The front surface morphology is the front view morphology. The double-sided interferometer mentioned in this embodiment includes a double-sided Fizeau interferometer or a double-sided Thyman Green interferometer, and the single-sided interferometer mentioned in this embodiment includes a single-sided Fizeau interferometer or a single-sided Thyman Green interferometer.

[0055] In some embodiments, the wafer can be placed horizontally or vertically. Taking a two-sided interferometer as an example, the interferometers located on both sides of the wafer can both be vertically incident interferometers, such as a two-sided Fizeau interferometer or a two-sided Thyman Green interferometer, or both can be obliquely incident interferometers, such as a two-sided grazing incident interferometer.

[0056] In some embodiments, adjacent partitions may or may not contain partially overlapping areas, as long as the complete wafer shape can be obtained after splicing.

[0057] In this embodiment, the height distribution map is a schematic diagram of the surface morphology. Based on the height distribution map, various morphology parameters can also be solved, such as warp and total thickness variation (TTV).

[0058] In some embodiments, dividing the wafer includes: obtaining the mode shape distribution of the wafer, and dividing the wafer according to the mode shape distribution. The advantage is that by dividing the wafer according to the mode shape distribution, the randomness of partitioning can be reduced, ensuring that locations with similar mode shapes are grouped into one partition, allowing subsequent steps to obtain a more accurate phase distribution map for each partition.

[0059] In some embodiments, the vibration distribution of the wafer is measured using existing mode shape analysis software. Candidate partitions on the wafer are obtained based on the mode shape distribution. One or more consecutive candidate partitions are used as one partition of the wafer, thereby dividing the wafer into multiple partitions. For example... Figures 2(a) to 2(c) As shown, a continuous region on the wafer with relatively close vibrations is a candidate partition. There are multiple candidate partitions on the wafer. For example, there are candidate partitions 101-109 on the wafer. Any two adjacent candidate partitions have different vibration modes, but it is not excluded that non-adjacent candidate partitions on the wafer may have the same or similar vibration modes.

[0060] In some embodiments, any candidate partition can be considered as one partition, thus the wafer is divided into 9 partitions; or multiple consecutive candidate partitions can be considered as one partition, for example, candidate partitions 101-103 can be considered as one partition, candidate partitions 104-106 can be considered as one partition, and candidate partitions 107-109 can be considered as one partition, thus the wafer is divided into 3 partitions.

[0061] In some embodiments, the wafer is provided with at least three support points, which are clamping points or supporting points. Dividing the wafer includes dividing the wafer by connecting adjacent support points. Its advantages are: it can reduce the randomness of partitioning, ensuring that positions with similar mode shapes are divided into one partition, allowing subsequent steps to obtain a more accurate phase distribution map for each partition.

[0062] In some embodiments, such as Figures 2(a)-2(c) As shown, the support points on the wafer are clamping points, and the wafer is clamped by a wafer clamping mechanism, which can be applied to dual-sided or single-sided interferometers; in some embodiments, the support points on the wafer are supporting points, and the wafer is supported by a wafer supporting mechanism, which includes, for example, a pin for supporting the wafer, and can be applied to single-sided interferometers.

[0063] In some embodiments, the wafer is held at its edge by a wafer clamping mechanism because it is necessary to avoid the wafer clamping mechanism affecting the topography measurement. However, the smaller the contact area between the wafer clamping mechanism and the wafer, the more susceptible the wafer is to environmental vibrations, resulting in lower accuracy of the wafer's surface topography measurement. However, the method described in this embodiment can improve the accuracy of surface topography measurement, and is therefore better suited for situations where the wafer is clamped by a wafer clamping mechanism.

[0064] For example, at least three clamping points are set, and their number and position are determined according to the actual situation. According to the mode shape analysis of the wafer, the vibration of the clamping point line and the area it encloses is small, while the vibration of the outer area is large. Therefore, the partitioning can be directly based on this mode shape distribution. Referring to Figures 2(a) and 2(b), an example of the position of the clamping point and partitioning is provided. Figure 2(b) is a schematic diagram of a wafer clamping mechanism clamping a wafer, which shows the positional relationship between the wafer clamping mechanism and a clamping point on the wafer. The clamping points on the front and back sides of the wafer are collinear along the axial direction of the wafer. Figure 2(a) shows the wafer clamped by the wafer clamping mechanism at clamping points 1, 2, and 3 on the wafer. By connecting adjacent clamping points 1, 2, and 3 in one direction (clockwise or counterclockwise), three line segments are obtained, forming partition 1, partition 2, partition 3, and partition 4. Partition 1 has smaller vibration, while partitions 2, 3, and 4 have larger vibration.

[0065] Combination Figures 2(a)-2(c) Based on the mode shape analysis of the wafer, it can be seen that after dividing the wafer by the connecting lines, each partition has a different mode shape. Therefore, dividing the wafer by connecting adjacent support points is essentially dividing the wafer based on mode shape analysis. Continuing with... Figures 2(a)-2(c) Although partition 1 does not fully include candidate partitions 104-106, partition 1 and its adjacent partitions 2, 3, or 4 all have different vibration modes, thus effectively distinguishing regions with different vibration modes on the wafer. It should be noted that the positions of partitions 1-4 in Figure 2(c) can be determined by referring to Figure 2(a). For example, partition 1 is indicated by a triangle surrounded by dashed lines in Figure 2(c).

[0066] In some embodiments, the wafer is clamped by a wafer clamping mechanism, and the clamping points are connected in a clockwise or counterclockwise direction to form a polygon with m sides. This divides the wafer into m+1 partitions, specifically including one partition enclosed by all the sides of the polygon, such as partition 1 in Figure 2(a); and m partitions formed by the sides of the polygon and the arc segments of the wafer, such as partitions 2, 3, and 4 in Figure 2(a). In some embodiments, the division of the wafer includes:

[0067] The wafer is divided into multiple concentric sector regions based on its center; or it is divided into a circular region and at least one annular region located around the circular region, the circular region and the annular region being concentric with respect to the center. The advantage is that by dividing the wafer according to its center (e.g., into multiple concentric and uniform sector regions), the mode shape distribution of the wafer does not need to be considered, making the operation simple and easy to implement.

[0068] In some embodiments, there is no overlap between any pair (or any group) of adjacent partitions, or at least one pair (or at least one group) of adjacent partitions has an overlapping region. It should be noted that, in order to obtain a complete wafer surface morphology, when there is no overlapping region, the boundaries of any pair of adjacent partitions should touch or be sufficiently close. Two adjacent partitions constitute a pair of partitions; the term "pair" can also be referred to as "group." In some embodiments, overlapping regions are beneficial for ensuring a complete wafer surface morphology.

[0069] In some embodiments, the overlapping region has phase data in different partitions. The phase data of the overlapping region is calculated as follows: when concatenating adjacent partitions with the overlapping region, the phase data of the overlapping region in one partition is used as the phase data of the overlapping region, or the average value of the phase data of the overlapping region in the partition is used as the phase data of the overlapping region. Taking two adjacent partitions with overlapping regions as an example, the overlapping region corresponds to two phase data from the two partitions. One of the phase data can be selected as the phase data of the overlapping region, or the average value of the two phase data can be taken as the phase data of the overlapping region.

[0070] For example, the wafer can be partitioned using the wafer center point in a manner including but not limited to sectors or concentric circles, such as... Figure 3 , Figure 4 As shown. In Figure 3 In the diagram, the circle with radius r1 closest to the center is a single partition, namely partition 1, which consists of circular region 301 and annular region 302. Partitions 2 and 3 are annular partitions. Partition 2 consists of annular regions 302, 303, and 304, and partition 3 consists of annular regions 304 and 305. Partition 2 overlaps with both partitions 1 and 3, meaning it has two overlapping regions. The annular width r' of the two overlapping regions is the same, and... Figure 3The partitions 2 and 3 shown have equal annular band widths r, represented as r2-r1+r' and r3-r2+r' respectively, where r2-r1=r3-r2, r' is the overlap width, satisfying N×(r-r')=R, where R is the wafer radius and N is the number of partitions. Figure 4 In this context, N partitions have the same angle, for example, N is 8, and θ is the angle size of each partition. Figure 4 Partition 1 and partition 2 are shown, θ' is the angle of the overlapping area between adjacent partitions, and N is the number of partitions, satisfying N×(θ-θ')=360°.

[0071] Specifically, the partitioning rule of dividing the wafer according to its mode shape distribution is compared with the partitioning rule of uniformly dividing the wafer according to its center. The former has the advantage of higher accuracy in calculating the vibration phase shift when using the phase shift algorithm in each partition; the latter does not consider the mode shape distribution of the wafer, but directly partitions the wafer into fan-shaped regions, resulting in lower accuracy in calculating the vibration phase shift, but it can save the time of mode shape analysis.

[0072] In some embodiments, processing at least three interference fringe patterns to obtain a phase distribution map for each partition includes: processing the at least three interference fringe patterns to obtain the wrapped phase corresponding to each partition; and unwrapping the wrapped phase to obtain a continuous phase distribution map corresponding to each partition. The advantage is that it obtains a continuous phase distribution map.

[0073] In some embodiments, after obtaining the phase distribution map of the wafer, the method further includes: obtaining the light intensity residual of the wafer by calculating the difference between the actual light intensity value (i.e., light intensity I) of the interference fringe pattern and the theoretical light intensity value (e.g., the theoretical light intensity value calculated using the formula mentioned above) at the corresponding position of the phase distribution map to be processed; comparing the light intensity residual with a preset threshold, and when the light intensity residual is greater than or equal to the preset threshold, re-dividing the wafer and obtaining the vibrational phase shift and phase distribution map of each partition after re-dividing the wafer; and stitching together the phase distribution maps of each partition after re-dividing to obtain the phase distribution map of the wafer. The beneficial effect is that, by comparing the light intensity residual with a preset threshold, and re-dividing the wafer when the light intensity residual is greater than or equal to the preset threshold, the accuracy of the wafer morphology measurement results is further improved. The preset threshold can be set according to actual conditions.

[0074] In some embodiments, the re-division of the wafer includes: obtaining the residual contribution value corresponding to each partition, and dividing the partition corresponding to the maximum residual contribution value according to the mode shape distribution of the partition corresponding to the maximum residual contribution value. The advantage is that re-dividing according to the partition corresponding to the maximum residual contribution value can improve efficiency.

[0075] In some embodiments, obtaining the residual contribution of each partition includes: obtaining the average value of the light intensity residual corresponding to each partition, and obtaining the residual contribution of each partition based on the average value, wherein the residual contribution is proportional to the average value. The beneficial effect is that re-dividing the partitions based on their large contribution to the light intensity residual can improve efficiency. Specifically, the residual contribution is obtained based on the average value and a set proportionality coefficient.

[0076] In some embodiments, the re-division of the wafer includes: changing the size of any one or more of the sector regions, or changing the size of any one or more of the circular regions and / or annular regions, to re-divide the wafer.

[0077] For example, after obtaining the phase distribution map of the wafer, the previously obtained partitions need to be evaluated. A preset threshold is set according to the phase measurement accuracy requirements. When the obtained light intensity residual is greater than or equal to the preset threshold, the partitions are re-performed. When re-partitioning, if the previous partitioning was based on the mode shape distribution of the wafer, the average value of the light intensity residuals of each partition can be further calculated and compared. The partition with the largest average value has the largest residual contribution. In this case, the partition with the largest residual contribution can be further partitioned according to the mode shape distribution of that region. For example, based on the results of the previous mode shape analysis, the partition can be re-partitioned. For example, one or more continuous regions can be used as a partition. If the residual contribution of partition 1 is the largest, then partition 1 can be re-partitioned into three partitions: continuous partition 104 to continuous partition 106. In addition, since the mode shape of the wafer may fluctuate at different times, mode shape analysis can be performed again, and partition 1 can be re-partitioned based on the results of this mode shape analysis. This will not be elaborated here. For partitioning based on the center of the wafer, the angle of the sector partition or the radius of the circular region and / or the width of the annular region can be adjusted. After re-partitioning, the light intensity residuals of the wafer can be re-subdivided until they meet the preset threshold condition, that is, the light intensity residuals are less than the preset threshold. The partitioning is then considered appropriate.

[0078] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A method for obtaining the surface morphology of a wafer, characterized in that, include: Collect at least three interference fringe patterns from the wafer; The wafer is divided to obtain multiple partitions on the wafer; At least three interference fringe patterns corresponding to each partition are processed to obtain the vibration phase shift of each partition, and the phase distribution pattern of each partition is obtained based on the vibration phase shift. The phase distribution maps of each partition are stitched together to obtain the phase distribution map of the wafer; After obtaining the phase distribution map of the wafer, the method further includes: obtaining the light intensity residual of the wafer by calculating the difference between the actual light intensity value of the interference fringe pattern and the theoretical light intensity value at the corresponding position; The light intensity residual is compared with a preset threshold. When the light intensity residual is greater than or equal to the preset threshold, the wafer is re-divided, and the vibration phase shift and phase distribution map of each partition after the wafer is re-divided are obtained. The phase distribution maps of the re-divided partitions are stitched together to obtain the phase distribution map of the re-stitched wafer. The phase distribution map after the wafer is reassembled is converted into a height distribution map to describe the surface morphology.

2. The method for obtaining the surface morphology of a wafer according to claim 1, characterized in that, The process of dividing the wafer includes: The mode shape distribution of the wafer is obtained, and the wafer is divided according to the mode shape distribution.

3. The method for obtaining the surface morphology of a wafer according to claim 1 or 2, characterized in that, The wafer is provided with at least three support points, which are clamping points or supporting points; the division of the wafer includes dividing the wafer by connecting adjacent support points.

4. The method for obtaining the surface morphology of a wafer according to claim 1, characterized in that, The process of dividing the wafer includes: The wafer is divided into multiple concentric sector regions based on its center; or it is divided into a circular region and at least one annular region located around the circular region, the circular region and the annular region being concentric with respect to the center.

5. The method for obtaining the surface morphology of a wafer according to claim 1, characterized in that, There is no overlapping area between any pair of adjacent partitions, or there is at least one pair of adjacent partitions with overlapping areas.

6. The method for obtaining the surface morphology of a wafer according to claim 5, characterized in that, When stitching together adjacent partitions with the overlapping region, the phase data of the overlapping region in one of the partitions is used as the phase data of the overlapping region, or the average value of the phase data of the overlapping region in the partitions is used as the phase data of the overlapping region.

7. The method for obtaining the surface morphology of a wafer according to claim 1, characterized in that, The re-division of the wafer includes: Obtain the residual contribution value corresponding to each partition, and divide the partition corresponding to the maximum value of the residual contribution value according to the mode distribution of the partition corresponding to the maximum value of the residual contribution value.

8. The method for obtaining the surface morphology of a wafer according to claim 7, characterized in that, Obtain the residual contribution value corresponding to each partition, including: The average value of the light intensity residual corresponding to each partition is obtained, and the residual contribution of each partition is obtained based on the average value. The residual contribution is proportional to the average value.

9. The method for obtaining the surface morphology of a wafer according to claim 4, characterized in that, The re-division of the wafer includes: The wafer may be redivided by changing the size of any one or more of the sector regions, or by changing the size of any one or more of the circular and / or annular regions.

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