A film thickness test structure and a method for real-time monitoring of light spot position during measurement

Abstract

The present invention provides a film thickness test structure and a method for real-time monitoring of the position of a light spot during a measurement process. The film thickness test structure includes a plurality of measurement blocks arranged in sequence and at intervals along the X direction. Each measurement block is correspondingly configured with a pair of numbered characters. The pair of numbered characters has four symmetrical feature points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serves as the center point of the measurement block. During the actual film thickness measurement process, the light spot is projected onto the measurement block, and the positions of the four symmetrical feature points of the pair of numbered characters corresponding to the measurement block are selected for capture and positioning, and their position coordinates are recorded. At the same time, the position coordinates of the light spot are recorded in real time, and then the position coordinates of the center point of the measurement block are calculated based on the recorded position coordinates of the four symmetrical feature points, and the offset of the light spot position relative to the center point position of the measurement block is calculated. The present invention can realize real-time monitoring of the actual measurement position of the online light spot, which is conducive to timely adjustment of the light spot position and obtaining accurate measurement results.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology and relates to a film thickness testing structure and a method for real-time monitoring of a light spot position during a measurement process. Background Art

[0002] A chip is a 3D structure composed of a series of active and passive circuit elements stacked together. Insulating dielectric films such as SiO2 and silicon nitride and metal conductive films such as Al and Cu are alternately stacked on the surface of the wafer through physical / chemical methods. Mask pattern transfer (photolithography), etching and other processes can be performed on the film to ultimately form the circuit structure of each layer.

[0003] During the wafer fabrication process, after thin film deposition is completed, the wafer lot must be transferred to a film thickness measurement machine for testing. If the beam deflects or the beam measurement position shifts during the actual THK measurement process, the measurement machine will output erroneous measurement results, leading to an OCAP (Out of Control Action Plan) online. Currently, engineers mostly determine beam position offset by inferring it from abnormal measurement results, which is time-consuming.

[0004] Therefore, how to improve the film thickness test structure and provide a method for real-time monitoring of the light spot position during the measurement process and timely adjust the actual light spot measurement position to ensure the accuracy of the measurement position and the accuracy of the output measurement results has become an important technical problem that needs to be solved urgently by technical personnel in this field.

[0005] It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a film thickness test structure and a method for real-time monitoring of the light spot position during the measurement process, so as to solve the problem of delay in determining the light spot position offset in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a method for real-time monitoring of the position of a light spot during a measurement process, comprising the following steps:

[0008] A wafer is provided, the wafer including a film thickness measurement area, the film thickness measurement area being provided with a plurality of measurement blocks sequentially and spaced apart along an X direction, each of the measurement blocks being correspondingly configured with a pair of numbered characters;

[0009] Projecting a light spot onto the measuring block, selecting four symmetrical feature points of a pair of numbered characters corresponding to the measuring block as four vertices of a rectangle, grasping and locating the positions of the four symmetrical feature points, and recording the position coordinates of the four symmetrical feature points in a preset coordinate system, while simultaneously recording the position coordinates of the light spot in the preset coordinate system in real time;

[0010] Taking the intersection of the two diagonals of the rectangle as the center point of the measurement block, and calculating the position coordinates of the center point of the measurement block according to the recorded position coordinates of the four symmetrical feature points;

[0011] The offset of the light spot position relative to the center point position of the measurement block is calculated according to the recorded light spot position coordinates and the calculated center point position coordinates of the measurement block.

[0012] Optionally, when the offset is less than a preset value, it is determined that the light spot position is located at the center of the measurement block;

[0013] When the offset is greater than a preset value, it is determined that the light spot position deviates from the center of the measuring block, and the offset is fed back to the machine end, and the relevant position parameters are adjusted until the offset is less than the preset value.

[0014] Optionally, after the offset is fed back to the machine end, the machine automatically adjusts the relevant position parameters until the offset is less than a preset value, or prompts the engineer to adjust the relevant position parameters through an alarm.

[0015] Optionally, the relevant position parameters include at least one of a spot size, an exposure field size, and a mechanical platform parameter.

[0016] Optionally, two numbered characters in a pair of numbered characters are arranged on both sides of the corresponding measurement block along the X direction and are mirror-symmetrical about the Y direction center axis of the corresponding measurement block, the Y direction is perpendicular to the X direction, the numbered characters corresponding to different measurement blocks have different shapes, and each numbered character is symmetrical about its own X direction center line.

[0017] Optionally, the numbering characters are selected from at least one of the letters I, C, D, E, B, H, K, O and X.

[0018] Optionally, a cross mark is provided at a preset position on the wafer, and the preset coordinate system uses the center of the cross mark as the coordinate origin.

[0019] Optionally, calculating the position coordinates of the center point of the measurement block according to the recorded position coordinates of the four symmetrical feature points includes:

[0020] A first straight line equation y1=k1x+b1 is obtained based on the position coordinates (x1, y1) and (x2, y2) of the two symmetrical feature points located on the first diagonal line of the rectangle, and a second straight line equation y2=k2x+b2 is obtained based on the position coordinates (x1, y2) and (x2, y1) of the two symmetrical feature points located on the second diagonal line of the rectangle;

[0021] According to the condition y1=y2, the center point position coordinates (x0, y0) of the corresponding measurement block are calculated.

[0022] Optionally, calculating the offset of the light spot position relative to the center point position of the measurement block includes:

[0023] The coordinates of the center point of the measuring block are marked as (x0, y0), and the coordinates of the light spot are marked as (x3, y3);

[0024] Use |x0-x3| as the x-direction offset and |y0-y3| as the y-direction offset.

[0025] Optionally, when the x-direction offset is smaller than a first preset value and the y-direction offset is smaller than a second preset value, it is determined that the light spot position is located at the center of the measurement block.

[0026] Optionally, the measuring block is rectangular in shape.

[0027] The present invention also provides a film thickness test structure, which is arranged in the film thickness measurement area of ​​the wafer, wherein the film thickness test structure includes multiple measurement blocks, and the multiple measurement blocks are arranged sequentially and at intervals along the X direction, and each measurement block is correspondingly configured with a pair of numbered characters, wherein the pair of numbered characters corresponding to the measurement block has four symmetrical feature points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serves as the center point of the measurement block.

[0028] Optionally, two numbered characters in a pair of numbered characters are arranged on both sides of the corresponding measurement block along the X direction and are mirror-symmetrical about the Y direction center axis of the corresponding measurement block, the Y direction is perpendicular to the X direction, the numbered characters corresponding to different measurement blocks have different shapes, and each numbered character is symmetrical about its own X direction center line.

[0029] Optionally, the numbering characters are selected from at least one of the letters I, C, D, E, B, H, K, O and X.

[0030] Optionally, the measuring block is rectangular in shape.

[0031] As described above, the present invention provides a film thickness test structure and a method for real-time monitoring of the position of a light spot during a measurement process, wherein the film thickness test structure is arranged in a film thickness measurement area of ​​a wafer and includes a plurality of measurement blocks arranged sequentially and spaced apart along the X direction, each measurement block is correspondingly configured with a pair of numbered characters, the pair of numbered characters having four symmetrical feature points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serving as the center point of the measurement block. During the actual film thickness measurement process, a light spot is projected onto the measurement block, and the four symmetrical feature points of the pair of numbered characters corresponding to the measurement block are selected as the four vertices of the rectangle. The positions of the four symmetrical feature points are captured and located, and the position coordinates of the four symmetrical feature points in a preset coordinate system are recorded, while the position coordinates of the light spot in the preset coordinate system are recorded in real time; then, the intersection of the two diagonals of the rectangle is used as the center point of the measurement block, and the position coordinates of the center point of the measurement block are calculated based on the recorded position coordinates of the four symmetrical feature points, and the offset of the light spot position relative to the center point position of the measurement block is calculated based on the recorded light spot position coordinates and the calculated position coordinates of the center point of the measurement block. The present invention can realize real-time monitoring of the actual measurement position of the light spot on the line, thereby facilitating timely adjustment of the light spot position and obtaining accurate measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Shown is a flow chart of the method for real-time monitoring of the light spot position during the measurement process of the present invention.

[0033] Figure 2 Displayed as a graphic of the film thickness measurement area.

[0034] Figure 3 A diagram showing a film thickness test structure used in the method for real-time monitoring of the light spot position during the measurement process of the present invention.

[0035] Figure 4 The diagram shows a method for real-time monitoring of the light spot position during the measurement process of the present invention, which selects specific symmetrical points in a symmetrical character to form a rectangle, cross-connects the end points of the rectangle, and uses the intersection of the rectangle cross-connection lines as the center point of the corresponding measurement block.

[0036] Figure 5 Schematic diagram showing the position coordinates of four symmetrical feature points and the position coordinates of the light spot in a plane rectangular coordinate system with the center O(0,0) of the cross mark as the coordinate origin in the method of real-time monitoring of the light spot position during the measurement process of the present invention.

[0037] Description of Reference Numerals

[0038] S1~S4 Steps 101 and 201 Measurement Block DETAILED DESCRIPTION

[0039] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0040] See also Figures 1 to 5 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0041] The present invention provides a film thickness test structure and a method for real-time monitoring of the light spot position during the measurement process. Figure 1 , shown as a flow chart of the method, comprising the following steps:

[0042] S1: providing a wafer, the wafer comprising a film thickness measurement area, the film thickness measurement area being provided with a plurality of measurement blocks sequentially and spaced apart along an X direction, each measurement block being correspondingly configured with a pair of numbered characters;

[0043] S2: Projecting a light spot onto the measurement block, selecting four symmetrical feature points of a pair of numbered characters corresponding to the measurement block as four vertices of a rectangle, grasping and locating the positions of the four symmetrical feature points, and recording the position coordinates of the four symmetrical feature points in a preset coordinate system, while simultaneously recording the position coordinates of the light spot in the preset coordinate system in real time;

[0044] S3: Taking the intersection of the two diagonals of the rectangle as the center point of the measurement block, and calculating the position coordinates of the center point of the measurement block according to the recorded position coordinates of the four symmetrical feature points;

[0045] S4: Calculating the offset of the light spot position relative to the center point position of the measurement block according to the recorded light spot position coordinates and the calculated center point position coordinates of the measurement block.

[0046] Specifically, in step S1 of the present invention, unique and symmetrical characters are designed to design the measurement block number (Pad No.), and these characters can be used to accurately locate the center position of the measurement block in the subsequent actual measurement process.

[0047] For comparison, see Figure 2, showing a graphic representation of a film thickness measurement area, where TK stands for thickness. Multiple measurement blocks 101 are arranged sequentially and spaced apart along the X direction. Each measurement block is assigned a corresponding numbered character on its left side. The numbered characters are named in alphabetical order, such as A, B, C, D, E, F, and G. These numbered characters serve only to identify the measurement blocks. In the present invention, each measurement block 201 is assigned a pair of numbered characters that serve as positioning symbols. These not only identify the measurement block but also allow accurate positioning of the center of the measurement block during actual measurement.

[0048] As an example, see Figure 3 , which shows a graphic of a film thickness test structure used in the present invention, wherein the film thickness test structure is arranged in a film thickness measurement area of ​​a wafer, wherein TK represents thickness.

[0049] Specifically, the film thickness test structure includes a plurality of measuring blocks 201, which are arranged in sequence and at intervals along the X direction. Each measuring block 201 is correspondingly configured with a pair of numbered characters, wherein the pair of numbered characters corresponding to the measuring block has four symmetrical feature points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serves as the center point of the measuring block.

[0050] As an example, two numbered characters in a pair of numbered characters are arranged on both sides of the corresponding measurement block 201 along the X direction and are mirror-symmetrical. The numbered characters corresponding to different measurement blocks 201 have different shapes, and each numbered character is symmetrical about its own X-direction center line.

[0051] As an example, the shape of the measurement block 201 is rectangular, and the number character is selected from at least one of the letters I, C, D, E, B, H, K, O and X.

[0052] Specifically, the positioning function of the symmetrical numbered characters in the present invention is reflected in that: a rectangle can be formed by selecting specific symmetrical points in the symmetrical characters, and the end points of the rectangles are cross-connected. The intersection of the rectangle cross-connections is the center point of the corresponding measurement block. For example, see Figure 4For a measurement block using a pair of numbered characters I, select the top point of the numbered character I on the left side of the measurement block as the first symmetrical feature point, select the bottom point of the numbered character I on the left side of the measurement block as the second symmetrical feature point, select the top point of the numbered character I on the right side of the measurement block as the third symmetrical feature point, and select the bottom point of the numbered character I on the right side of the measurement block as the fourth symmetrical feature point, wherein the first symmetrical feature point and the second symmetrical feature point are symmetrical about the X-direction centerline of the numbered character itself, the third symmetrical feature point and the fourth symmetrical feature point are symmetrical about the X-direction centerline of the numbered character itself, the first symmetrical feature point and the third symmetrical feature point are mirror-symmetric about the Y-direction center axis of the measurement block, and the second symmetrical feature point and the fourth symmetrical feature point are mirror-symmetric about the Y-direction center axis of the measurement block. For other symmetrical numbered characters, the selection of the four symmetrical feature points satisfies the above principles.

[0053] Specifically, the measurement block 201 includes the film layer to be measured at the top. For example, in one embodiment, the measurement block 201 includes a Si layer, a TEOS layer, and an Al layer stacked sequentially from bottom to top. The area surrounding the measurement block 201 includes the Si layer and TEOS layer stacked sequentially from bottom to top, but does not include the Al layer to be measured. In step S2, an ellipsometer or other suitable film thickness measurement device can be used to project a light spot onto the measurement block 201. Subsequently, by inverting the polarization state of the reflected light, the film thickness information of the film to be measured can be obtained, thereby achieving film thickness measurement.

[0054] Specifically, during the film thickness measurement process, four symmetrical feature points of a pair of numbered characters corresponding to the measuring block 201 are selected as the four vertices of the rectangle, the positions of the four symmetrical feature points are captured and located, and the position coordinates of the four symmetrical feature points in the preset coordinate system are recorded, and the position coordinates of the light spot in the preset coordinate system are recorded in real time.

[0055] As an example, a cross mark is provided at a preset position on the wafer, and the preset coordinate system uses the center of the cross mark as the coordinate origin.

[0056] As an example, see Figure 5 , which is displayed as the position coordinates of the four symmetrical feature points and the position coordinates of the light spot in a plane rectangular coordinate system with the center O(0, 0) of the cross mark as the coordinate origin.

[0057] As an example, the calculation of the position coordinates of the center point of the measurement block 201 according to the recorded position coordinates of the four symmetrical feature points in step S3 includes the following process:

[0058] (1) A first straight line equation y1=k1x+b1 is obtained based on the position coordinates (x1, y1) and (x2, y2) of the two symmetrical feature points located on the first diagonal line of the rectangle (the diagonal line running diagonally upward from left to right), and a second straight line equation y2=k2x+b2 is obtained based on the position coordinates (x1, y2) and (x2, y1) of the two symmetrical feature points located on the second diagonal line of the rectangle (the diagonal line running diagonally downward from left to right);

[0059] (2) According to the condition y1=y2 (i.e., the intersection of the two straight lines), the coordinates of the center point of the corresponding measurement block (x0, y0) are calculated.

[0060] As an example, the step S4 of calculating the offset of the light spot position relative to the center point position of the measurement block includes the following process:

[0061] (1) The coordinates of the center point of the measurement block are marked as (x0, y0), and the coordinates of the light spot are marked as (x3, y3);

[0062] (2) Use |x0-x3| as the x-direction offset and |y0-y3| as the y-direction offset.

[0063] As an example, after calculating the offset of the light spot position relative to the center point of the measurement block in step S4, the following judgment step is further performed:

[0064] When the offset is less than a preset value, it is determined that the light spot position is located at the center of the measurement block;

[0065] When the offset is greater than a preset value, it is determined that the light spot position deviates from the center of the measuring block, and the offset is fed back to the machine end, and the relevant position parameters are adjusted until the offset is less than the preset value.

[0066] As an example, when the x-direction offset is less than a first preset value and the y-direction offset is less than a second preset value, it is determined that the light spot position is located at the center of the measurement block, wherein the first preset value and the second preset value can be set according to the actual process and are not specifically limited in the present invention.

[0067] As an example, when the x-direction offset is greater than a first preset value and / or the y-direction offset is greater than a second preset value, it can be determined that the spot position deviates from the center of the measuring block. At this time, the offset is fed back to the machine end, and the relevant position parameters are adjusted until the offset is less than the preset value.

[0068] In some embodiments, after the offset is fed back to the machine, the machine automatically adjusts the relevant position parameters until the offset is less than a preset value.

[0069] In other embodiments, after the offset is fed back to the machine, the machine prompts the engineer to adjust the relevant position parameters through an alarm.

[0070] As an example, the relevant position parameters include but are not limited to at least one of a spot size, an exposure field size, and a mechanical platform parameter.

[0071] Specifically, adjusting the spot size is, for example, increasing or decreasing the diameter of the spot, for example, adjusting the spot size to 10 microns or other suitable sizes.

[0072] Specifically, the exposure field (wafer shot) is also called the light field. It refers to the size of the area covered by each exposure when the photolithography machine performs photolithography on the wafer during the semiconductor manufacturing process. The size of the exposure field directly affects the number and layout of integrated circuits that can be manufactured on the wafer. The exposure field size is usually expressed in area units, such as square millimeters (mm 2 ) or square micrometer (μm 2 ), this size can be set according to the requirements of the process technology. For example, in one embodiment, the exposure field size is adjusted to 10 microns × 10 microns or other suitable sizes as needed.

[0073] Specifically, the mechanical stage in this invention refers to the "stage wafer," which is used to position and move wafers within a lithography machine or other semiconductor manufacturing equipment. This mechanical stage must possess a high degree of precision and stability, as it directly impacts the positioning accuracy of transistors and other components on the wafer, which in turn affects the performance and yield of the entire chip. In this invention, when the light spot position is determined to be deviating from the center of the measurement block, the mechanical stage parameters can be adjusted as needed to improve transfer position accuracy and help align the light spot center with the measurement block center.

[0074] At this point, the present invention has designed a measurement-symmetrical measurement block number, which can accurately locate the center position of the measurement block during the actual measurement process. The position coordinates of the center point of the measurement block can be calculated through the position coordinates of the actual measurement number character feature points, and compared with the actual light spot position in real time. It can monitor in real time whether the light spot on the line is deviated, which helps to adjust the actual light spot measurement position in time, thereby ensuring the measurement position accuracy and the accuracy of the output measurement results.

[0075] In summary, the present invention provides a film thickness test structure and a method for real-time monitoring of the position of a light spot during a measurement process, wherein the film thickness test structure is arranged in a film thickness measurement area of ​​a wafer and includes a plurality of measurement blocks arranged sequentially and at intervals along the X direction, each measurement block is correspondingly configured with a pair of numbered characters, the pair of numbered characters having four symmetrical feature points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serving as the center point of the measurement block. During the actual film thickness measurement process, a light spot is projected onto the measurement block, and the four symmetrical feature points of the pair of numbered characters corresponding to the measurement block are selected as the four vertices of the rectangle. The positions of the four symmetrical feature points are captured and located, and the position coordinates of the four symmetrical feature points in a preset coordinate system are recorded, while the position coordinates of the light spot in the preset coordinate system are recorded in real time; then, the intersection of the two diagonals of the rectangle is used as the center point of the measurement block, and the position coordinates of the center point of the measurement block are calculated based on the recorded position coordinates of the four symmetrical feature points, and the offset of the light spot position relative to the center point position of the measurement block is calculated based on the recorded light spot position coordinates and the calculated position coordinates of the center point of the measurement block. The present invention can monitor the actual measurement position of the light spot on the line in real time, thereby facilitating timely adjustment of the light spot position and obtaining accurate measurement results. Therefore, the present invention effectively overcomes various shortcomings of the existing technology and has high industrial application value.

[0076] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for real-time monitoring of the position of a light spot during a measurement process, characterized in that: The following steps are involved: A wafer is provided, the wafer including a film thickness measurement area, the film thickness measurement area being provided with a plurality of measurement blocks sequentially and spaced apart along an X direction, each of the measurement blocks being correspondingly configured with a pair of numbered characters; Projecting a light spot onto the measuring block, selecting four symmetrical feature points of a pair of numbered characters corresponding to the measuring block as four vertices of a rectangle, grasping and locating the positions of the four symmetrical feature points, and recording the position coordinates of the four symmetrical feature points in a preset coordinate system, while simultaneously recording the position coordinates of the light spot in the preset coordinate system in real time; Taking the intersection of the two diagonals of the rectangle as the center point of the measurement block, and calculating the position coordinates of the center point of the measurement block according to the recorded position coordinates of the four symmetrical feature points; The offset of the light spot position relative to the center point position of the measurement block is calculated according to the recorded light spot position coordinates and the calculated center point position coordinates of the measurement block.

2. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: When the offset is less than a preset value, it is determined that the light spot position is located at the center of the measurement block; When the offset is greater than a preset value, it is determined that the light spot position deviates from the center of the measuring block, and the offset is fed back to the machine end, and the relevant position parameters are adjusted until the offset is less than the preset value.

3. The method for real-time monitoring of the light spot position during the measurement process according to claim 2, characterized in that: When the offset is fed back to the machine, the machine automatically adjusts the relevant position parameters until the offset is less than the preset value, or prompts the engineer to adjust the relevant position parameters through an alarm.

4. The method for real-time monitoring of the light spot position during the measurement process according to claim 3, characterized in that: The relevant position parameters include at least one of a spot size, an exposure field size, and a mechanical platform parameter.

5. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: The two numbered characters in a pair of numbered characters are arranged on both sides of the corresponding measurement block along the X direction and are mirror-symmetrical about the Y direction center axis of the corresponding measurement block, and the Y direction is perpendicular to the X direction. The numbered characters corresponding to different measurement blocks have different shapes, and each numbered character is symmetrical about its own X direction center line.

6. The method for real-time monitoring of the light spot position during the measurement process according to claim 5, characterized in that: The number character is selected from at least one of the letters I, C, D, E, B, H, K, O and X.

7. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: A cross mark is provided at a preset position on the wafer, and the preset coordinate system uses the center of the cross mark as the coordinate origin.

8. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: Calculating the position coordinates of the center point of the measurement block according to the recorded position coordinates of the four symmetrical feature points includes: A first straight line equation y1=k1x+b1 is obtained based on the position coordinates (x1, y1) and (x2, y2) of the two symmetrical feature points located on the first diagonal line of the rectangle, and a second straight line equation y2=k2x+b2 is obtained based on the position coordinates (x1, y2) and (x2, y1) of the two symmetrical feature points located on the second diagonal line of the rectangle; According to the condition y1=y2, the center point position coordinates (x0, y0) of the corresponding measurement block are calculated.

9. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: Calculating the offset of the spot position relative to the center point of the measurement block includes: The coordinates of the center point of the measuring block are marked as (x0, y0), and the coordinates of the light spot are marked as (x3, y3); Use |x0-x3| as the x-direction offset and |y0-y3| as the y-direction offset.

10. The method for real-time monitoring of the light spot position during the measurement process according to claim 9, characterized in that: When the x-direction offset is smaller than a first preset value and the y-direction offset is smaller than a second preset value, it is determined that the light spot position is located at the center of the measurement block.

11. The method for real-time monitoring of the light spot position during the measurement process according to claim 1, characterized in that: The measuring block is in a rectangular shape.

12. A film thickness test structure, disposed in a film thickness measurement area of ​​a wafer, characterized in that: The film thickness test structure includes a plurality of measurement blocks, which are arranged in sequence and at intervals along the X direction, and each measurement block is correspondingly configured with a pair of numbered characters, wherein the pair of numbered characters corresponding to the measurement block has four symmetrical characteristic points located at the four vertices of a rectangle, and the intersection of the two diagonals of the rectangle serves as the center point of the measurement block; A light spot is projected onto the measuring block, and the film thickness information of the film to be measured is obtained by performing information inversion on the reflected light.

13. The film thickness testing structure according to claim 12, wherein: The two numbered characters in a pair of numbered characters are arranged on both sides of the corresponding measurement block along the X direction and are mirror-symmetrical about the Y direction center axis of the corresponding measurement block, and the Y direction is perpendicular to the X direction. The numbered characters corresponding to different measurement blocks have different shapes, and each numbered character is symmetrical about its own X direction center line.

14. The film thickness testing structure according to claim 13, wherein: The number character is selected from at least one of the letters I, C, D, E, B, H, K, O and X.

15. The film thickness testing structure according to claim 12, wherein: The measuring block is in a rectangular shape.

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