Automatic focusing method, measurement method and measurement module

Abstract

The invention provides an automatic focusing method, a measurement method and a measurement module, and the method comprises the steps: obtaining the height value of any point on the surface of a calibration wafer in m working regions, and calculating the height difference value between any two working regions in different working regions relative to the surface of the calibration wafer; m is an integer greater than or equal to 2; obtaining a first height value of a selected point on the surface of the to-be-measured wafer in the first working area through an automatic focusing system, and calculating a second height value corresponding to the selected point when the to-be-measured wafer moves to the second working area based on a height difference value between the first working area and the second working area; and automatically focusing a selected point on the surface of the wafer to be measured in the second working area based on the second height value. According to the invention, on the premise that an automatic focusing system is not added, each set of optical measurement module can be rapidly and accurately positioned to the position of the focus, and the accuracy of the wafer when the wafer is measured under the plurality of sets of optical measurement modules is improved.

Description

Technical Field

[0001] The invention belongs to the field of automatic focusing, and relates to an automatic focusing method, a measuring method and a measuring module. Background Art

[0002] In the process of integrated circuit manufacturing, optical measurement modules are widely used for non-destructive measurement of the thickness, optical constants, key dimensions and other properties of various semiconductor films. At present, in order to obtain the best measurement effect, equipment manufacturers usually integrate multiple sets of measurement modules into the same device. The multiple sets of measurement modules can be optical measurement modules of various different modes, such as optical ellipsometer and single-wavelength ellipsometer system, or measurement modules of different principles are integrated, such as optical measurement modules and electron beam measurement modules. When selecting an optical measurement module, it is necessary to ensure the accuracy of the system's autofocus, especially when integrating multiple measurement modules in the same chamber of the same device. How to ensure that the autofocus system maintains good performance in the working area of ​​multiple measurement modules has become a difficult problem that the industry needs to solve urgently.

[0003] In the prior art, there is a solution of using one set of optical measurement modules to correspond to one set of automatic focusing systems, that is, using multiple sets of automatic focusing systems when integrating multiple sets of optical measurement modules. However, the optical measurement modules are limited by the mechanical space, and the equipment equipped with multiple sets of measurement modules cannot simultaneously have multiple sets of automatic focusing systems corresponding to nearby positions. This is because the focus of the automatic focusing system needs to be confocal with the focus of the optical measurement module to obtain the best measurement effect. When multiple sets of measurement modules share one set of automatic focusing systems, the actual focus position of the optical measurement module installed far away from the automatic focusing system will introduce deviations due to the mechanical platform, thereby reducing the accuracy of the system measurement. Therefore, it is necessary to further study and improve the measurement method of the automatic focusing system of multiple measurement modules to improve the measurement accuracy of the system.

[0004] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides an automatic focusing method, a measuring method and a measuring module, which can obtain a first height value of a selected point on the wafer surface through an automatic focusing system on the basis of obtaining the height difference of each point on the wafer surface in multiple working areas, thereby calculating a second height value of the wafer surface, and realizing automatic focusing of a selected point on the surface of the wafer to be measured in the second working area according to the second height value.

[0006] Specifically, the present invention provides an automatic focusing method, which at least includes:

[0007] Obtaining the measured height value of any point on the calibration wafer surface in m working areas, and calculating the height difference between any two working areas in different working areas relative to the calibration wafer surface; m is an integer greater than or equal to 2;

[0008] Acquire a first height value of a selected point on the surface of the wafer to be measured in a first working area through an automatic focusing system, and calculate a second height value corresponding to the selected point when the wafer to be measured moves to the second working area based on the height difference between the first working area and the second working area;

[0009] Automatically focusing a selected point on the surface of the wafer to be measured in the second working area based on the second height value.

[0010] Optionally, the automatic focusing method further includes automatically focusing a selected point on the surface of the wafer to be measured in the first working area based on the automatic focusing system.

[0011] Optionally, the first height value is simultaneously acquired when the first working area automatically focuses on a selected point on the surface of the wafer to be measured.

[0012] Optionally, a specific method for calculating the height difference includes:

[0013] Set any point on the surface of the calibration wafer as a measurement point, and move the measurement point to the center position of m working areas, and record the height value of the measurement point corresponding to each center position; the center positions of the working areas do not overlap with each other;

[0014] The difference between each height value is calculated to obtain the height difference between any two areas in different working areas.

[0015] Optionally, the first working area and the second working area partially overlap.

[0016] Optionally, the measured height value of any point on the surface of the calibration wafer is greater than the first height value and the second height value of the selected point of the wafer to be measured.

[0017] The present invention also provides a measurement method for measuring the physical properties of a wafer to be measured, the measurement method at least comprising:

[0018] Adjusting the automatic focusing system to be confocal with the first working area, and focusing the second working area based on the automatic focusing method according to any one of claims 1 to 6;

[0019] The surface of the wafer to be measured is optically measured by a first optical measurement module; the surface of the wafer to be measured is optically measured by a second optical measurement module; the working area of ​​the first optical measurement module is used as the first working area, and the working area of ​​the second optical measurement module is used as the second working area.

[0020] Optionally, the specific steps of performing optical measurement on the surface of the wafer to be measured include setting multiple measurement points on the surface of the wafer to be measured; selecting any measurement point from the multiple measurement points as a selected point and performing optical measurement under the first optical measurement module and the second optical measurement module respectively; and then adjusting an unselected measurement point from the multiple measurement points as a selected point, and performing optical measurement under the first optical measurement module and the second optical measurement module respectively.

[0021] The present invention also provides a measuring device for implementing the aforementioned measuring method, comprising: the measuring system comprises: the first optical measuring module, the second optical measuring module, the automatic focusing system and at least two measuring modules;

[0022] The first optical measurement module is used to perform optical measurement on the surface of the wafer to be measured and the working area serves as the first working area;

[0023] The second optical measurement module is used to perform optical measurement on the wafer to be measured as the second working area;

[0024] Two measuring modules are respectively arranged above each working area to obtain the measured height value of any point on the surface of the wafer to be measured in different working areas;

[0025] The automatic focusing system is disposed above the first working area and is confocal with the first working area, and is used to obtain a first height value of a selected point on the wafer surface in the first working area.

[0026] Optionally, the first optical measurement module and the second optical measurement module include at least one of an optical ellipsometric measurement system and a single-wavelength ellipsometric measurement system.

[0027] Optionally, the measurement system further includes a wafer carrying component; the wafer carrying component carries the wafer and moves the wafer to different working areas.

[0028] Optionally, the measurement system further comprises a host computer, which receives each measured height value and is used to calculate the height difference value, and automatically focuses on a selected point on the wafer surface in the second working area based on the second height value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1It is a schematic flow chart of the measuring method of the present invention.

[0030] Figure 2 Shown is a framework diagram of the autofocus mechanism of the present invention.

[0031] Figure 3 Shown is a schematic diagram of the motion trajectory of the wafer of the present invention.

[0032] Figure 4 Shown is a color schematic diagram of the height values ​​of various points on the wafer surface measured by the first optical measurement module of the present invention.

[0033] Figure 5 Shown is a color diagram of the height values ​​of various points on the wafer surface measured by the second optical measurement module of the present invention.

[0034] Figure 6 Shown is a structural schematic diagram of the measurement module of the present invention.

[0035] Component number description

[0036] 1 Measurement method

[0037] S1~S4 measurement steps

[0038] 2 Measuring device

[0039] 20 Measurement modules

[0040] 21a First optical measurement module

[0041] 21b Second optical measurement module

[0042] 22 Autofocus system

[0043] 23 Loading platform

[0044] 230 working area

[0045] 24 Wafer Carrier Components

[0046] 241 First working area

[0047] 242 Second working area

[0048] 25 Fixed parts

[0049] 26 Support components DETAILED DESCRIPTION

[0050] The following is an explanation of the embodiments of the present invention by specific examples. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0051] See also Figures 1 to 6. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any structural decoration, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0052] like Figure 1 As shown, this embodiment provides an automatic focusing method 1, through the embodiment provided as Figure 2 The automatic focusing mechanism shown is implemented as follows. The automatic focusing mechanism includes: a first optical measurement module 21 a, a second optical measurement module b, an automatic focusing system 22 and at least two measurement modules 20 .

[0053] like Figure 2 As shown, the first optical measurement module 21a is used to perform optical measurement on the surface of the wafer to be measured and the working area is used as the first working area. The second optical measurement module b performs optical measurement on the surface of the same wafer to be measured and the working area is used as the second working area.

[0054] Specifically, the first optical measurement module 21a and the second optical measurement module 21b include at least one of an optical ellipsometer measurement module and a single-wavelength ellipsometer measurement module. In this embodiment, the first optical measurement module 21a is configured as an optical ellipsometer measurement module; the second optical measurement module 21b is configured as a single-wavelength ellipsometer measurement module. The specific measurement module configuration is not limited to this embodiment, and can also be configured as an optical measurement module integrated with an electron beam measurement module.

[0055] like Figure 2 As shown, two measuring modules 20 are respectively arranged above each working area, and are used to obtain the measured height value of any point on the surface of the wafer to be measured in different working areas.

[0056] Specifically, in this embodiment, Figure 6As shown, the measurement module 20 is set as a displacement sensor with the characteristics of fast response speed, high linearity, high repeatability, low failure rate and low power consumption. By using a displacement sensor to measure the height without contacting the wafer, wear on the wafer is avoided, reliability is further improved and service life is extended, and the consistency and accuracy of the measurement results can be ensured. At the same time, since the displacement sensor has the characteristics of low failure rate and low power consumption, and can be reused as a tool in this embodiment, costs can be saved during the subsequent hardware integration of the measuring device 2. In actual use, any device that can measure the measured height value of each point on the wafer is applicable to the present invention, and will not be described one by one here.

[0057] More specifically, in this embodiment, the automatic focusing mechanism further includes a level and a parallelism measuring component (not shown in the figure), wherein the level is used to adjust the horizontal position of each measuring module 20 installed on the fixing component 25, and the parallelism measuring component is used to adjust the vertical position of each measuring module 20 installed on the fixing component 25 (in this embodiment, by Figure 6 As shown, the parallelism on the fixed component 25 is fixed by the fixed component 25. Ensure that the spacing between each measuring module 20 and the wafer carrier component 24 is equal when it is fixed on the fixed component 25. In actual use, any device that can ensure that the spacing between each measuring module and the wafer carrier component is equal when it is fixed is applicable to the present invention, and will not be described one by one here. It can be understood that when there is a situation where it is impossible to achieve equal spacing between each measuring module 20 and the wafer carrier component 24 when it is fixed on the fixed component 25, the corresponding height difference can be recorded to correct the calculation process of the height difference value in the subsequent scheme.

[0058] like Figure 2 As shown, the automatic focusing system 22 is arranged above the first optical measurement module a, and is used to automatically focus on the selected point on the surface of the wafer to be measured in the first working area. At the same time, the automatic focusing system 22 can also obtain the first height value of the selected point on the surface of the wafer to be measured in the first working area.

[0059] Specifically, affected by the performance indicators of mechanical hardware such as runout, straightness, and levelness, such as the levelness of the plane that carries the wafer, when the wafer is placed on the carrying platform and moves on the horizontal plane, the heights of various points on the wafer are actually not consistent. When the wafer moves between multiple working areas, each point on the wafer will correspond to different Z-direction height values ​​(Z-direction is the vertical direction perpendicular to the horizontal plane) under multiple measurement systems.

[0060] In this embodiment, the two optical measurement modules have independent working areas under the carrying platform. The first working area 241 and the second working area 242 are designed according to the actual space in the chamber. In order to achieve compact space, the first working area 241 and the second working area 242 can partially overlap, such as Figure 3 As shown. It can be understood that the center position of the first working area 241 and the center position of the second working area 242 are still different, so as to avoid the inability to measure the height value of each point on the wafer under the corresponding measurement module. Among them, the wafer is placed on the carrier device and moves horizontally and along the Z axis between different working areas in the chamber, so that the optical measurement modules corresponding to different working areas can perform corresponding automatic focusing and measurement.

[0061] In this embodiment, two measuring modules 20 are arranged in the vertical direction of the center position of the corresponding working area to measure the wafer surface height.

[0062] It should be noted that the measured height value of any point on the surface of the calibrated wafer is greater than the first height value and the second height value of the selected point of the wafer to be measured. The height values ​​tested by the two measuring modules 20 are not the same as the first height value measured by the automatic focusing system 22. The height values ​​tested by the two measuring modules 20 are relative to the surface of the wafer, and the first height value obtained based on the automatic focusing system 22 is the Z-axis coordinate value of the height of the entire wafer.

[0063] It should be emphasized that the autofocus system 22 is a system with complex operation and precise testing, and occupies a larger space than the measurement module 20. Although multiple autofocus systems 22 can also measure the height of the surface of the wafer to be tested in different working areas, they are more expensive and are limited by mechanical space. Two autofocus systems 22 cannot overlap. When the distance between the first working area 241 and the second working area 242 is close or even partially overlapped (such as Figure 3 As shown in the figure, when there is a phenomenon of overlap between the two working areas), the two automatic focusing systems 22 cannot be used at the same time, so that the volume of the automatic focusing mechanism will become larger during measurement, and the accuracy of the equipment will be affected.

[0064] This embodiment provides an automatic focusing method 1, such as Figure 1 As shown, the automatic focusing mechanism mentioned above is implemented, including:

[0065] S1. Obtain the measured height value of any point on the surface of the calibration wafer in m working areas, and calculate the height difference between any two working areas in different working areas relative to the surface of the calibration wafer; m is an integer greater than or equal to 2.

[0066] Specifically, as an example, a specific method for calculating the height difference includes: setting any point on the surface of the calibration wafer as a measurement point, and moving the measurement point to the center position of m working areas, and recording the height value of the measurement point corresponding to each center position; wherein the center positions of the working areas do not overlap with each other, that is, to ensure that the wafer will be displaced when moving in each working area. The difference between each height value is calculated to obtain the height difference between any two areas in different working areas. It should be noted that other points in the working area can also be set for measurement, which is not limited to this embodiment. As long as the setting of the relative height difference between the two working areas can be ensured through the same wafer, it is within the protection scope of this embodiment.

[0067] In this step, the calibration wafer can be selected as a standard wafer for measurement, or the calibration wafer surface can be set as the wafer to be measured, that is, the wafer surface and the wafer surface to be measured are set to the same wafer surface to improve the detection accuracy. Figure 3 As shown, two sets of motion trajectories are provided for subsequent comparison. At the same time, in order to facilitate the subsequent repeated detection and application, the measurement module takes the center of the standard wafer as the coordinate origin, and collects the dot coordinates of each point on the standard wafer in the first working area corresponding to the optical ellipsometric measurement module on the horizontal plane, and records them as: (X11, Y11), (X12, Y12), ..., (X1n, Y1n); then the dot coordinates of each point on the standard wafer in the second working area corresponding to the second optical measurement module are collected on the horizontal plane, and recorded as: (X21, Y21), (X22, Y22), ..., (X2n, Y2n), where n is a natural number greater than or equal to 1. At the same time, the Z-direction height value (Z direction, i.e., the direction perpendicular to the horizontal plane) corresponding to the dot coordinates of each point on the standard wafer is recorded as: (Z11, Z12, ..., Z1n) in the first working area; and recorded as: (Z21, Z22, ..., Z2n) in the second working area.

[0068] Combine the following Figure 4 and Figure 5 Explain the above height difference calculation:

[0069] like Figure 4 As shown, in actual use, the Z-direction height values ​​of each point on the standard wafer (when the selected point is set to multiple) at the first working area include but are not limited to 517.00170 mm (such as Figure 4 The right edge of the display), 517.53770mm (such as Figure 4 The left edge of the display), 518.07370mm, 519.14580mm, 521.82570mm (such as Figure 4That is, the heights of various points on the wafer are shown by the different colors of the Z-direction height values.

[0070] like Figure 5 As shown, in actual use, the Z-direction height values ​​of each point on the standard wafer at the second working area include but are not limited to 380.51240 mm (such as Figure 5 ), 380.94920mm, 381.38600mm, 381.82280mm, 382.47790mm (such as Figure 5 That is, the heights of various points on the wafer are shown by the different colors of the Z-direction height values.

[0071] At the same time, combined Figure 4 and Figure 5 As shown in the figure, by comparing the color difference of the Z-direction height values ​​of each point on the standard wafer under the two optical measurement modules, it is shown that the height values ​​of each point on the standard wafer at different positions are different. The Z-direction height values ​​corresponding to each point on the standard wafer at the two positions are subtracted one by one, and the height difference ΔZn obtained corresponds to the height difference of each point on the wafer surface: (ΔZ1, ΔZ2, ..., ΔZn) where ΔZn = Z2n-Z1n.

[0072] S2. Obtain a first height value of a selected point on the surface of the wafer to be measured in the first working area through the automatic focusing system 22, and calculate a second height value corresponding to the selected point when the wafer to be measured moves to the second working area based on the height difference between the first working area and the second working area.

[0073] Specifically, the automatic focusing method further includes automatically focusing a selected point on the surface of the wafer to be measured in the first working area based on the automatic focusing system 22 .

[0074] In this embodiment, the first height value is obtained simultaneously when the first working area 241 is automatically focused on the selected point on the surface of the wafer to be measured. The surface of the wafer to be measured in the first working area corresponding to the first optical measurement module 21a (optical ellipsometric measurement module) is focused by the automatic focusing system 22, and the focus Z-axis height value is read as the first height value of the current focus measurement point when the focus setting is completed.

[0075] It should be noted that, specifically in this embodiment, when obtaining the first height value, the first height value may be obtained after automatically focusing on all measurement points set by the current system, or the first height value corresponding to a point may be obtained after automatically focusing on only a certain measurement point. In addition, in this embodiment, the measurement point corresponding to the first height value should belong to the point selected in step one, so as to realize reading the corresponding height data from the height difference set in step one through the coordinates of the measurement point corresponding to the first height value.

[0076] It should be further explained that accurate, precise and fast autofocus is necessary during optical ellipsometric measurement. Since the autofocus system 22 and the optical measurement modules (the first optical measurement module 21a and the second optical measurement module 21b) are independent of each other, there is still a certain height difference in space, especially a certain difference in the confocal point. In this embodiment, in order to further improve the accuracy, it is necessary to calibrate the height offset (i.e., Focus Offset) between the focus of the autofocus system 22 and the first optical measurement module 21a in advance. During real-time measurement, after ensuring that the autofocus system 22 and the optical measurement module have a drop only in the height direction (i.e., the projection on the horizontal plane is the same point), the autofocus system 22 can be used to focus and add the height offset and then move to the second optical measurement module 21b for measurement to improve the measurement accuracy. In this embodiment, the focus of the autofocus system 22 and any one of the optical measurement modules is confocal, and after achieving confocality, the first height value of each point on the wafer under the first optical measurement module 21a is obtained by the autofocus system 22. At the same time, it should be ensured that the vertical projection of each measuring module on the horizontal plane and the vertical projection of the focus of the corresponding optical measuring module on the horizontal plane are located at the same point (vertical projection is a projection perpendicular to the horizontal plane), so that the measurement results are more accurate and the error is smaller.

[0077] Specifically, in this embodiment, in order to realize the switching between multiple optical measurement modules, the wafer to be tested is generally carried by the wafer carrying component 24 to move between multiple working areas. For example, the first working area corresponding to the first optical measurement module 21a is moved to the second working area corresponding to the second optical measurement module 21b. As before, in order to realize that when the wafer to be tested moves to the second working area, each point on the wafer to be tested can be focused by the same set of automatic focusing system 22, this embodiment uses the collected height difference value and the measured first height value for calculation, and obtains the second height value to facilitate the subsequent automatic focusing of the wafer in the second working area. Specifically, the second height value is the first height value and the height difference value ΔZ n For example, if the coordinates of the wafer measurement point are (x, y), the corresponding (X 1n , Y 1n )、(X2n ,

[0078] Y 2n ), and the corresponding ΔZ n , the first height value measured by the current measuring point in the first working area and the height difference ΔZ n By adding them together, the focusing height of the current measuring point in the second working area can be calculated.

[0079] As before, the second height value of the measurement unit in the second working area can be calculated for each measurement point and then moved to the next measurement module, or the second height value can be calculated for all measurement points of the wafer to be measured and then moved to the next measurement module to perform the corresponding measurement task.

[0080] S3. Automatically focusing on a selected point on the surface of the wafer to be measured in the second working area based on the second height value.

[0081] Specifically, in this embodiment, after obtaining the second height value corresponding to each point on the wafer in the second working area, the wafer is moved to the height position corresponding to the second working area for automatic focusing. That is, this embodiment does not need to set up another automatic focusing system 22 in the second working area for automatic focusing.

[0082] like Figure 6 As shown, this embodiment further provides a measuring device 2, including the above-mentioned automatic focusing mechanism, whose specific structure has been described in the foregoing text and will not be repeated here.

[0083] Specifically, the measuring device 2 further includes a wafer carrying component 24; the wafer carrying component 24 carries the wafer to be measured and moves the wafer to be measured to different working areas. Figure 6 As shown, the fixing component 25 is fixedly arranged above the wafer carrying component 24; the upper surface of the carrying platform 23 is set as the working area 230, and the wafer carrying component 24 is arranged on the upper surface of the carrying platform 23; and the wafer carrying component 24 moves in the working area 230.

[0084] In this embodiment, the carrying platform 23 is configured as a marble carrying platform with uniform structure, good stability, high precision and strong wear resistance, etc., for carrying the moving wafer carrying component 24. In actual use, any device capable of carrying the moving wafer carrier component is applicable to the present invention, and will not be described in detail here.

[0085] Specifically, the measuring device also includes a fixing component 25 and a supporting component 26. Before optical measurement, each measuring module 20 is set on the fixing component 25; it is used to obtain the height value of the same point on the wafer under the two optical measuring modules. In this embodiment, the measuring module 2 also includes a supporting component 26, which is arranged on the edge of the supporting platform 23 and the fixing component 25 to fix the fixing component 25 and provide a moving area (i.e., a working area 230) for the wafer supporting component 24. In actual use, any method that can fix the fixing component is applicable to the present invention, and will not be described one by one here.

[0086] like Figure 6 As shown, when multiple optical measurement systems are installed, each measurement module is removed, and the autofocus system 22 and each optical measurement system 21 are set on the fixed component 25, and the focus of the autofocus system 22 and any ellipsometric measurement system 21 is confocal, and the first height value of each point on the wafer is obtained based on the autofocus system 22.

[0087] It should be noted that after each measurement module 20 measures the height value of each point on the wafer under each measurement module 20, each measurement module 20 needs to be removed (when starting measurement), and then the automatic focusing system 2222 is installed at the corresponding position of any optical measurement module for testing to avoid the automatic focusing system 22 being unable to be accurately fixed on the fixing component 25, resulting in the projection of the focus of the automatic focusing system 22 on the horizontal plane and the optical measurement.

[0088] Specifically, the measurement system also includes a host computer (not shown in the figure) which receives each measured height value and is used to calculate the height difference value, and automatically focuses on a selected point on the wafer surface in the second working area based on the second height value.

[0089] More specifically, in this embodiment, the host computer receives the measured height values ​​measured by each measurement module 20 and obtains the height difference value after processing, and then receives the first height value corresponding to each point on the wafer measured by the automatic focusing system 22. Finally, the host computer adds the height difference value and the first height value to obtain the second height value of each point on the wafer under the second ellipsometric measurement module 21, and automatically focuses each point on the wafer based on the second height value. In actual use, any device that can receive and process data of the height values ​​measured by each measurement module and the first height value measured by the automatic focusing system 22 is applicable to the present invention, and is not limited to this embodiment.

[0090] This embodiment also provides a measurement method, which is implemented based on the above-mentioned measurement device and is used to measure the physical characteristics of the wafer to be measured, including: adjusting the autofocus system to be confocal with the first working area 241, and focusing the second working area 2242 based on the above-mentioned autofocus method. The surface of the wafer to be measured is optically measured by the first optical measurement module 21a; the surface of the wafer to be measured 21b is optically measured by the second optical measurement module; the working area of ​​the first optical measurement module 21a is used as the first working area 241, and the working area of ​​the second optical measurement module 21b is the second working area 242. That is, under the premise that the autofocus system is confocal with the first working area 241, the surface of the wafer to be measured is optically measured by the first optical measurement module 21a, and under the premise of the above-mentioned autofocus method, the surface of the wafer to be measured is optically measured by the second optical measurement module 21b.

[0091] Specifically, in the present embodiment, the specific steps of optically measuring the surface of the wafer to be measured include setting a plurality of measuring points on the surface of the wafer to be measured; selecting any measuring point from the plurality of measuring points as a selected point and performing optical measurement under the first optical measurement module 21a and the second optical measurement module 21b respectively; and adjusting an unselected measuring point from the plurality of measuring points as a selected point and performing optical measurement under the first optical measurement module 21a and the second optical measurement module 21b respectively.

[0092] In this embodiment, when performing thin film measurement on the wafer to be measured, it is generally performed point by point, for example, by presetting multiple measurement points on the surface of the wafer, and measuring each measurement point one by one, so as to complete the measurement task set by the system. In the device integrating multiple measurement modules, after performing the measurement tasks of different measurement modules on the current measurement point, it is possible to switch to the next point and then measure it, or after the current measurement module performs all measurement points, it is possible to move to another measurement module to measure all measurement points. Regardless of the method used, automatic focusing of the measurement point is required before measuring different measurement points.

[0093] In addition, it should be noted that the measurement method provided in this embodiment is suitable for multiple sets of optical measurement modules and is not limited to the two sets of measurement modules requiring automatic focusing provided in this embodiment. The specific principles have been described in the previous text and will not be repeated here.

[0094] In summary, the present invention provides an automatic focusing method, a measuring method and a measuring module, wherein the automatic focusing method comprises: obtaining the height value of any point on the surface of a calibrated wafer in m working areas, and calculating the height difference between any two working areas in different working areas relative to the surface of the calibrated wafer; m is an integer greater than or equal to 2; obtaining the first height value of a selected point on the surface of a wafer to be measured in a first working area through an automatic focusing system, and calculating the second height value corresponding to the selected point when the wafer to be measured moves to the second working area based on the height difference between the first working area and the second working area; and automatically focusing the selected point on the surface of the wafer to be measured in the second working area based on the second height value. The present invention ensures that each set of optical measurement modules can quickly and accurately locate the focus position without increasing the automatic focusing system, thereby improving the accuracy of the wafer when being measured under multiple sets of optical measurement modules. At the same time, it also avoids one set of optical measurement modules corresponding to one set of automatic focusing systems, further saving space and installation time. Therefore, the present invention effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0095] 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An automatic focusing method, characterized in that: The automatic focusing method comprises: Obtaining the measured height value of any point on the calibration wafer surface in m working areas, and calculating the height difference between any two working areas in different working areas relative to the calibration wafer surface; m is an integer greater than or equal to 2; Acquire a first height value of a selected point on the surface of the wafer to be measured in a first working area through an automatic focusing system, and calculate a second height value corresponding to the selected point when the wafer to be measured moves to the second working area based on the height difference between the first working area and the second working area; Automatically focusing a selected point on the surface of the wafer to be measured in the second working area based on the second height value.

2. The automatic focusing method according to claim 1, characterized in that: The automatic focusing method further includes automatically focusing a selected point on the surface of the wafer to be measured in the first working area based on the automatic focusing system.

3. The automatic focusing method according to claim 2, characterized in that: The first height value is simultaneously acquired when the first working area automatically focuses on a selected point on the surface of the wafer to be measured.

4. The automatic focusing method according to claim 1, characterized in that: The specific method for calculating the height difference includes: Set any point on the surface of the calibration wafer as a measurement point, and move the measurement point to the center position of m working areas, and record the height value of the measurement point corresponding to each center position; the center positions of the working areas do not overlap with each other; The difference between each height value is calculated to obtain the height difference between any two areas in different working areas.

5. The automatic focusing method according to claim 4, characterized in that: The first working area and the second working area partially overlap.

6. The automatic focusing method according to claim 1, characterized in that: The measured height value of any point on the surface of the calibration wafer is greater than the first height value and the second height value of the selected point of the wafer to be measured.

7. A measurement method for measuring the physical properties of a wafer to be measured, characterized in that: The measuring method comprises: Adjusting the automatic focusing system to be confocal with the first working area, and focusing the second working area based on the automatic focusing method according to any one of claims 1 to 6; The surface of the wafer to be measured is optically measured by a first optical measurement module; the surface of the wafer to be measured is optically measured by a second optical measurement module; the working area of ​​the first optical measurement module is used as the first working area, and the working area of ​​the second optical measurement module is used as the second working area.

8. The measuring method according to claim 7, characterized in that: The specific steps of optically measuring the surface of the wafer to be measured include setting multiple measurement points on the surface of the wafer to be measured; selecting any measurement point from the multiple measurement points as a selected point and performing optical measurement under the first optical measurement module and the second optical measurement module respectively; and adjusting an unselected measurement point from the multiple measurement points as a selected point, and performing optical measurement under the first optical measurement module and the second optical measurement module respectively.

9. A measuring device for implementing the measuring method according to claim 7 or 8, characterized in that: The measurement system comprises: the first optical measurement module, the second optical measurement module, the automatic focusing system and at least two measurement modules; The first optical measurement module is used to perform optical measurement on the surface of the wafer to be measured and the working area serves as the first working area; The second optical measurement module is used to perform optical measurement on the wafer to be measured as the second working area; Two measuring modules are respectively arranged above each working area to obtain the measured height value of any point on the surface of the wafer to be measured in different working areas; The automatic focusing system is disposed above the first working area and is confocal with the first working area, and is used to obtain a first height value of a selected point on the wafer surface in the first working area.

10. The measuring device according to claim 9, characterized in that: The first optical measurement module and the second optical measurement module include at least one ellipsometric measurement system in an optical ellipsometric measurement system and a single-wavelength ellipsometric measurement system; And / or, the measurement system further comprises a wafer carrying component; the wafer carrying component carries the wafer and moves the wafer to different working areas; And / or, the measurement system further comprises a host computer, which receives each measured height value and is used to calculate the height difference value, and automatically focuses on a selected point on the wafer surface in the second working area based on the second height value.

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