Double-layer scanning interference measurement equipment and method for measuring whole shape of wafer

Abstract

The invention relates to double-layer scanning interference measurement equipment and a double-layer scanning interference measurement method for measuring the whole shape of a wafer. The double-layer scanning interference measurement method for measuring the whole shape of the wafer comprises the following steps: acquiring the size of the wafer to be detected and the local scanning range of a movable probe; according to the size of a wafer to be detected and the local scanning range, dividing the wafer to be detected into a plurality of local detection areas which are adjacent to one another and have a preset overlapping amount; generating a scanning path of the movable probe according to the divided local measuring areas; according to the scanning path, a mobile platform used for bearing a wafer to be detected is controlled to move, so that the movable probe sequentially enters each local detection area, and after the movable probe completes scanning of the current local detection area, the movable probe enters the next local detection area until all the local detection areas complete scanning; and splicing the scanning data of each local measurement area to generate a whole wafer morphology graph.

Description

Technical Field

[0001] This invention relates to the field of measurement technology, and in particular to a dual-layer scanning interferometry apparatus and method for measuring the morphology of a whole wafer. Background Technology

[0002] In the semiconductor manufacturing process, the surface morphology, flatness, warpage trend, and local undulation features of the wafer directly affect subsequent processes such as photolithography, thin film deposition, bonding, and packaging. Therefore, high-precision full-wafer morphology inspection is required.

[0003] Existing wafer topography inspection equipment typically uses optical interferometry to obtain surface height information. Due to the limited field of view in a single measurement, when measuring an entire wafer, it is usually necessary to rely on an external stage to move the wafer multiple times relative to the measurement head in order to achieve sequential measurement of multiple measurement areas and subsequent stitching.

[0004] For example, Chinese patent document CN106292238A discloses a reflective off-axis digital holographic microscopy measurement device, which reconstructs the three-dimensional morphology of a sample through a beam splitter, a reference optical path, an object optical path, and multiple mirrors. While this type of solution can perform optical morphology measurement, its technical focus is mainly on optical path construction and reference optical path adjustment. For large-scale measurement scenarios covering an entire wafer, it is still necessary to rely on an external platform or other relative motion mechanisms to achieve multi-area coverage.

[0005] For example, Chinese patent document CN112325765B discloses an optical microscopy measurement system that expands the measurement field of view through internal scanning, which can expand the measurement range under the conditions of fixed working distance and high spatial resolution. This type of solution has certain advantages in expanding the coverage of a single measurement, but its main focus is on the internal scanning to expand the field of view itself. It does not provide specific solutions for how the internal scanning mechanism and the external XY platform coordinate during the whole wafer measurement process, how to reduce the number of platform movements, and how to establish a unified global coordinate system.

[0006] For example, Chinese patent document CN103217125A discloses a wafer surface morphology measurement device and method. This type of solution can realize wafer surface morphology measurement, but it usually still achieves measurement coverage of different areas by moving the stage. There is still room for further optimization in terms of multi-size wafer switching, maintaining a unified measurement benchmark, and measurement area splicing efficiency.

[0007] In summary, while existing technologies disclose solutions such as optical interferometry, internal scanning to expand the field of view, and wafer topography measurement equipment, the following problems still exist in practical applications: When relying mainly on an external XY platform for multi-region coverage, the platform needs to be frequently started, stopped, and repositioned, and after each movement, it is necessary to wait for the platform to stabilize, which can easily increase the overall measurement cycle time; platform movement introduces additional vibrations, affecting local measurement stability and stitching errors between adjacent measurement areas; in multi-size wafer switching scenarios, if the measurement reference depends on an external carrier or sample posture, recalibration is often required, resulting in low switching efficiency; some solutions also need to rely on wafer edges, notches, or alignment marks to establish a global coordinate system, increasing the complexity of coordinate establishment and recognition processing.

[0008] Therefore, it is still necessary to provide a new wafer full-wafer topography measurement device to reduce the number of external platform actions, shorten measurement time, and maintain a uniform measurement benchmark when switching between wafers of different sizes while ensuring measurement coverage.

[0009] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0010] The main objective of this invention is to provide a dual-layer scanning interferometry device and method for measuring the morphology of a whole wafer, aiming to solve the aforementioned technical problems in the prior art.

[0011] To achieve the above objectives, the present invention provides a dual-layer scanning interferometry apparatus for measuring the topography of a whole wafer, comprising: Mobile platform; A wafer carrier, mounted on the mobile platform, is used to carry the wafer to be tested; An optical measurement device is disposed above the wafer carrier. The optical measurement device includes a movable probe and a reference mirror. The reference mirror and the measurement optical path of the movable probe together form an interferometric measurement reference. The movable probe is used to perform non-contact interferometric measurement on the surface of the wafer to be inspected. The controller is connected to both the mobile platform and the optical measurement device, and is configured to: Obtain the dimensions of the wafer to be inspected, as well as the local scanning range of the movable probe; Based on the size of the wafer to be inspected and the local scanning range, the wafer to be inspected is divided into several adjacent local measurement areas with a preset overlap. Based on the divided local measurement areas, the scanning path of the movable probe is generated; According to the division of each local measurement area, the mobile platform is controlled to move so that the movable probe enters each local measurement area in sequence. At the same time, according to the scanning path, after the movable probe completes the scanning of the current local measurement area, the mobile platform is controlled to move so that the movable probe enters the next local measurement area, until all local measurement areas have been scanned. The scanning data from each local measurement area are stitched together to generate a full wafer topography image.

[0012] In the dual-scan interferometry apparatus for measuring the topography of a whole wafer, the controller is further configured to: Based on the divided local test areas, the moving platform is controlled to move the wafer to be tested to a preset position corresponding to the corresponding local test area; When the wafer to be inspected moves to the preset position, the movable probe is controlled to complete the scanning of the current local measurement area according to the scanning path; When the current local measurement area is completed, the mobile platform is controlled to move so that the movable probe can enter the next local measurement area, until all local measurement areas are completed.

[0013] In the dual-scan interferometry apparatus for measuring the topography of a whole wafer, the controller is further configured to: When the movable probe completes the scanning of the current local measurement area and the next local measurement area is within the current local scanning range, the movable probe is controlled to complete the scanning of the current local scanning range. When the movable probe completes the scanning of the current local measurement area and the next local measurement area is outside the current local scanning range, the mobile platform is controlled to move so that the movable probe enters the next local measurement area.

[0014] In the dual-scan interferometry apparatus for measuring the topography of a whole wafer, the controller is further configured to: The positioning information of the mobile platform when the movable probe is in each local measurement area, and the pre-calibrated coordinate system relative position relationship between the mobile platform and the movable probe are obtained. Based on the positioning information and the relative positional relationship of the coordinate system, the scanning data of each local measurement area are converted to the same global coordinate system; The scan data, converted to the same global coordinate system, are stitched together to generate a full wafer topography image.

[0015] In the dual-layer scanning interferometry apparatus used for full-wafer morphology measurement, the step of stitching together the scan data transformed to the same global coordinate system to generate a full-wafer morphology image includes: Based on the preset overlap amount and global coordinates, determine the spatial overlap range between adjacent local survey areas; Fuse two sets of scan data within a defined spatial overlap range; The fused scan data are stitched together to generate a full wafer topography image.

[0016] In the dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer, after the step of fusing two sets of scanning data within a determined spatial overlap range, and before the step of stitching together all the fused scanning data to generate a whole wafer morphology image, the method further includes: Calculate the stitching error between the two scan data within the spatial overlap range; After the step of stitching together all the fused scan data to generate a full wafer topography image, the method further includes: Determine whether the suture error exceeds a preset error threshold to obtain a first determination result; If the first judgment result is yes, the local measurement area corresponding to the scan data is determined to be an abnormal measurement area, and the abnormal measurement area is remeasured.

[0017] In the dual-scan interferometry apparatus for measuring the topography of a whole wafer, the controller is further configured to: When the difference between the stitching error and the preset error threshold is less than the first threshold, the overlap between the two local measurement areas corresponding to the stitching error is increased.

[0018] In the dual-layer scanning interferometry apparatus for measuring the morphology of the entire wafer, the movable range of the movable probe corresponds to the local scanning range; And / or, The movable probe performs point-to-point movement via an encoder-driven mechanism.

[0019] In the dual-layer scanning interferometric measurement device for measuring the morphology of the entire wafer, the optical measurement device is a planar array infrared interferometer. The planar array infrared interferometer is also equipped with a reference mirror. The reference mirror and the measurement optical path of the movable probe together form an interferometric measurement reference.

[0020] To achieve the above objectives, the present invention provides a dual-layer scanning interferometry method for measuring the topography of a whole wafer, the dual-layer scanning interferometry method for measuring the topography of a whole wafer comprising: Obtain the dimensions of the wafer to be inspected, as well as the local scanning range of the movable probe; Based on the size of the wafer to be inspected and the local scanning range, the wafer to be inspected is divided into several adjacent local measurement areas with a preset overlap. Based on the divided local test areas, a scanning path for the movable probe is generated; based on the scanning path, the moving platform used to carry the wafer to be tested is controlled to move so that the movable probe enters each local test area in sequence, and enters the next local test area after the movable probe completes the scanning of the current local test area, until all local test areas have been scanned. The scanning data from each local measurement area are stitched together to generate a full wafer topography image.

[0021] The present invention has at least the following beneficial effects: This invention forms a dual-layer scanning structure by simultaneously setting up a movable probe for local scanning and a mobile platform outside the device. It can prioritize the measurement of a single local measurement area through internal local scanning, and only drive the platform to switch areas when necessary, thereby reducing the number of times the external platform is started and stopped.

[0022] Furthermore, due to the reduced number of movements of the moving platform, the stabilization waiting time after each movement is correspondingly reduced, and the impact of moving platform vibration on local measurement results is suppressed. Therefore, it helps to reduce the measurement cycle time of the entire wafer. Especially in 6-inch wafer applications, it can save tens of seconds of measurement time.

[0023] Furthermore, the present invention establishes a global coordinate system based on the relative positional relationship between the pre-calibrated mobile platform and the area array infrared interferometer, without relying on wafer edge, notch or alignment mark identification, which simplifies the whole-wafer coordinate establishment process and improves the system applicability and measurement process stability.

[0024] Furthermore, this invention integrates a reference mirror into the area array infrared interferometer and designs multi-size wafer carriers based on known reference distances, so that wafers of different sizes can still work along a unified measurement reference after switching, without the need for recalibration, thereby improving the efficiency of wafer changeover.

[0025] Furthermore, by stitching local data under a unified global coordinate system and evaluating its quality, this invention can control the repeatability and stitching error between adjacent test areas, thereby facilitating the acquisition of stable wafer morphology data. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an embodiment of the dual-layer scanning interferometry measurement system for measuring the morphology of a whole wafer provided by the present invention; Figure 2 The flowchart of the double-scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in the first embodiment; Figure 3 The flowchart of the double-layer scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in a second embodiment; Figure 4 A flowchart of the double-layer scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in the third embodiment; Figure 5 The flowchart of the double-layer scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in the fourth embodiment; Figure 6 The flowchart of the double-layer scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in the fifth embodiment; Figure 7 The flowchart of the double-layer scanning interferometry method for measuring the morphology of a whole wafer provided by the present invention in the sixth embodiment is shown.

[0027] 1-Mobile platform, 2-Wafer carrier, 3-Optical measurement device.

[0028] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0030] In this embodiment of the invention, the term "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0032] In this embodiment of the invention, the term "multiple" refers to two or more, and other quantifiers are similar.

[0033] In this invention, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the embodiments of the present invention to facilitate a better understanding of the invention. However, the technical solutions claimed in the present invention can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined with and referenced by each other without contradiction.

[0035] The present invention provides a dual-scanning interferometry device for measuring the morphology of a whole wafer, used to detect the test area of ​​the wafer to be tested. The dual-scanning interferometry device for measuring the morphology of a whole wafer includes a vibration isolation platform, a moving platform 1, a wafer carrier 2, an optical measurement device 3, and a controller.

[0036] The vibration isolation platform is a support structure used to ensure measurement accuracy. In some embodiments, the vibration isolation platform is made of highly stable marble, utilizing the high density, low coefficient of thermal expansion, low internal stress, and good long-term stability of marble to provide a physical reference platform with extremely high flatness and resistance to temperature changes for the entire measurement system. The vibration isolation platform provides a stable and reliable motion reference for the XY moving platform 1 mounted on it—when the moving platform 1 moves between different local measurement areas, the vibration isolation platform ensures that the geometric accuracy of the guide rail flatness, motion straightness, etc., of the moving platform 1 is not affected by external vibrations; when the moving platform 1 remains stationary during measurement in a local measurement area, the vibration isolation platform further suppresses residual vibrations that may be caused by the movement of surrounding equipment or personnel, enabling the optical measurement device 3 to complete high-precision interferometric scanning in a near-static environment.

[0037] The moving platform 1 is the key motion actuator for achieving efficient measurement of the entire wafer. Preferably, the moving platform 1 is an XY moving platform 1, mounted on a vibration-isolated platform, used to support the wafer carrier 2 and drive the wafer under test to perform a wide-range, high-precision stepping motion in the horizontal plane. The moving platform 1 and the wafer carrier 2 use a unified mechanical mounting reference and positioning interface, ensuring that the relative positional relationship between the platform and the measuring instrument does not need to be recalibrated after replacing wafer carriers 2 of different sizes.

[0038] The wafer carrier 2 is mounted on the moving platform 1 and is used to carry the wafer to be tested. The size of the wafer carrier 2 can be determined according to the size of the wafer to be tested. The wafer carrier 2 can typically be configured with multiple sizes.

[0039] An optical measurement device 3 is positioned above the wafer carrier 2. The optical measurement device 3 includes a movable probe and a reference mirror. The reference mirror and the measurement optical path of the movable probe together form an interferometric measurement reference. The movable probe is used for non-contact interferometric measurement of the wafer surface to be inspected. The movable probe can perform local scanning within its movable range. The movable range of the movable probe corresponds to the local scanning range. In some embodiments, the local scanning range is 80mm × 80mm. That is, when the moving platform 1 is stationary, the movable probe can scan and measure the area within the local scanning range. The movable probe can, but is not limited to, use an encoder-driven mechanism to perform point-to-point movement. The movable range of the movable probe corresponds to the local scanning range.

[0040] In some embodiments, the optical measuring device 3 can be a planar infrared interferometer, which is further equipped with a reference mirror inside. The reference mirror and the measuring optical path of the movable probe together form an interferometric measurement reference.

[0041] Because the reference mirror is integrated inside the measuring instrument, the reference standard does not change depending on the replacement of the external wafer carrier 2. Therefore, wafer carriers 2 of different sizes preferably adopt a unified mounting standard and a unified height standard design, ensuring that after wafers of different sizes are loaded, a known reference distance is maintained between the surface of the wafer under test and the area array infrared interferometer. Thus, after switching between wafer carriers 2 of different sizes, the equipment can directly perform measurements without re-establishing the measurement standard.

[0042] The controller is connected to both the mobile platform 1 and the optical measuring device 3. When controlling the movable probe according to a preset scanning path, the controller can move between multiple discrete points and collect local topographic data at each point. The preset scanning path can be a serpentine path, a grid path, a reciprocating path, or other feasible paths. In other embodiments, the movable probe can also achieve local area coverage by combining continuous trajectory scanning with discrete sampling, as long as it can complete the scanning measurement of the local measurement area without driving the external mobile platform 1.

[0043] Figures 2 to 7 The flowchart illustrates the dual-layer scanning interferometry method for full-wafer topography measurement provided by this invention. This method can be used... Figure 1 This can be performed using a dual-scan interferometry apparatus for measuring the topography of the entire wafer, or any other suitable computer equipment. Alternatively, it can be performed specifically through the controller of a dual-scan interferometry apparatus for measuring the topography of the entire wafer.

[0044] Specifically, Figure 2The diagram illustrates a first embodiment of the dual-scan interferometry method for measuring the topography of a whole wafer provided by the present invention.

[0045] Please see Figure 2 In step S1000, the dimensions of the wafer to be inspected and the local scanning range of the movable probe are obtained. The dimensions of the wafer to be inspected can be manually input by the user beforehand, or they can be obtained by reading the wafer's identifier and retrieving pre-stored size information corresponding to that identifier; alternatively, they can be automatically obtained through other scanning methods, without specific limitations. The local scanning range of the movable probe is the maximum area that the movable probe can independently scan while driving the external moving platform 1.

[0046] In step S2000, based on the size of the wafer to be inspected and the local scanning range, the wafer is divided into several adjacent local measurement areas with a preset overlap. By dividing the wafer to be inspected, the whole-wafer measurement is performed locally rather than as a whole task. By actively setting a preset overlap between adjacent local measurement areas (e.g., 5%-15% edge overlap), adjacent measurement areas will spatially cover a common area. This provides redundant information for subsequent data stitching, allowing the stitching algorithm to use the extra data in the overlapping area to eliminate the boundary step effect; it can also compensate for possible platform positioning errors or probe motion errors, ensuring complete coverage between adjacent measurement areas even with small positional deviations; in addition, it provides a comparative data source for stitching error calculation and quality assessment.

[0047] In step S3000, the scanning path of the movable probe is generated based on the divided local measurement areas. The movable probe switches between local measurement areas by controlling the movement of the moving platform 1. For example, after completing the scanning of one local measurement area, the moving platform 1 moves to ensure that the next local measurement area of ​​the wafer under test is within the local scanning range of the movable probe. For each local measurement area, the scanning trajectory can be planned according to the motion characteristics of the movable probe and the measurement accuracy requirements. For example, it can be a serpentine path, a grid path, a reciprocating path, or other feasible paths. The paths for each local measurement area can be the same or different, depending on the size of each divided local measurement area and the local scanning range.

[0048] In step S4000, the mobile platform 1 is controlled to move according to the divided local measurement areas so that the movable probe enters each local measurement area in sequence. At the same time, after the movable probe completes the scanning of the current local measurement area according to the scanning path, the mobile platform 1 is controlled to move so that the movable probe enters the next local measurement area, until all local measurement areas have been scanned.

[0049] Assume the wafer under test is divided into three local measurement areas, with scanning paths A1, A2, and A3 respectively. First, the moving platform 1 moves the wafer under test until the movable probe is at a preset position a1 corresponding to the first local measurement area. At this point, the movable probe remains stationary; only the moving platform 1 moves. When the movable probe is at preset position a1 relative to the wafer under test, the movable probe moves and scans along the scanning path A1, completing the scan of the first local measurement area. Next, the moving platform 1 moves the wafer under test until the movable probe is at a preset position a2 corresponding to the second local measurement area. The movable probe scans along the scanning path A2, completing the scan of the second local measurement area. Finally, the moving platform 1 moves the wafer under test until the movable probe is at a preset position a3 corresponding to the third local measurement area. The movable probe scans along the scanning path A3, completing the scan of the third local measurement area.

[0050] Step S5000 stitches together the scanning data of each local measurement area to generate a full wafer topography image.

[0051] Figure 3 The diagram illustrates a second embodiment of the dual-scanning interferometry method for measuring the topography of a whole wafer provided by the present invention. Figure 3 A specific embodiment of step S4000 is given. Step S4000 may include steps S4100 to S4300.

[0052] Step S4100 involves controlling the movement of the mobile platform 1 according to the divided local measurement areas, moving the wafer to be tested to a preset position corresponding to the local measurement area. By controlling the movement of the mobile platform 1, a specific area of ​​the wafer to be tested is precisely transported into the working field of view of the optical measurement device 3. Specifically, according to the pre-divided local measurement area sequence (such as serpentine sequence, spiral sequence, or center-priority sequence), the target position of the current measurement area in the global coordinate system is obtained, and then the mobile platform 1 is controlled to drive the wafer carrier 2 to perform a large-range stepping movement until the preset center point (or measurement area starting point) of the current measurement area is aligned with the optical axis center of the area array infrared interferometer.

[0053] The "preset position" in this step is not a fixed absolute coordinate, but a relative position dynamically calculated based on the survey area division results—each local survey area corresponds to a unique platform target coordinate. Since the mobile platform 1 only needs to complete the area-changing positioning within the local survey area, rather than undertaking fine movement within the local survey area, each movement of the mobile platform 1 is a long-stroke step, reducing the number of starts and stops and lowering the stabilization waiting time. After reaching the target position, the mobile platform 1 remains stationary, providing a stable mechanical environment for subsequent local scanning.

[0054] In step S4200, when the wafer to be tested moves to the preset position, the movable probe is controlled to complete the scanning of the current local test area according to the scanning path.

[0055] This step is the execution phase of local measurement, fully utilizing the high-precision, high-speed scanning capabilities of the internal movable probe. Once the moving platform 1 reaches the preset position and stabilizes, the scanning task of the movable probe is immediately initiated. Based on the pre-generated scanning path (such as a serpentine path, grid path, or reciprocating path) for the measurement area, motion commands are sent to the drive mechanism (preferably an encoder drive mechanism) of the movable probe. The movable probe moves point-by-point or continuously within the local scanning range according to the planned trajectory. At each sampling point, the area array infrared interferometer synchronously acquires the interference signal from the wafer surface and calculates the high-precision height data for that point using the internally integrated reference mirror and the interference reference of the measurement optical path.

[0056] During this process, two key pieces of information are recorded in real time: first, the absolute position coordinates of the current mobile platform 1 (the position of mobile platform 1 corresponding to this survey area); and second, the local coordinates of the movable probe within the area array infrared interferometer (the probe position at the current sampling point). These two pieces of information, combined with the pre-calibrated relative positional relationship between the mobile platform 1 and the area array infrared interferometer, ensure that the height data of each sampling point can be converted to the global coordinate system in real time. Throughout the scanning process, the mobile platform 1 remains stationary, and all scanning tasks are completed independently by the movable probe. This avoids vibration interference from the movement of the mobile platform 1 on the precision interferometry, ensuring the accuracy and repeatability of data within the local survey area.

[0057] In step S4300, when the current local measurement area is scanned, the mobile platform 1 is controlled to move so that the movable probe can enter the next local measurement area, until all local measurement areas are scanned. This step achieves seamless switching between local measurement areas, ensuring the continuity and integrity of the entire measurement. After the movable probe completes the scanning task of the current local measurement area, it first determines whether there are any unmeasured local measurement areas: if all measurement areas have been scanned, the measurement process ends and enters the data processing stage; if there are still local measurement areas to be measured, the measurement area switching process begins. According to the preset local measurement area sequence, the platform target position corresponding to the next local measurement area to be measured is obtained, and the mobile platform 1 is controlled to move from the current position to the preset position of the next local measurement area. During the movement of the mobile platform 1, the movable probe remains in standby mode and does not perform scanning actions. After the mobile platform 1 reaches the new position and stabilizes, step S4200 is repeated to control the movable probe to complete the scanning of the new local measurement area. This cycle continues until all local measurement areas are scanned.

[0058] It is worth noting that this step follows the scheduling principle of "local scanning priority, platform area replacement for supplementation." This means that, from the current platform position, the movable probe is used as much as possible to scan adjacent measurement areas, and platform movement is only triggered when the remaining measurement area exceeds the probe's movable range. This scheduling strategy minimizes the number of platform movements, thereby reducing the time overhead and vibration interference introduced by platform start-up and shutdown, and improving overall measurement efficiency. For example, in the full-wafer measurement of a 6-inch wafer, this intelligent scheduling can reduce the number of platform movements from hundreds in traditional methods to just over ten, saving tens of seconds in the overall measurement cycle time.

[0059] Figure 4 This diagram illustrates a third embodiment of the dual-scan interferometry method for measuring the topography of a whole wafer provided by the present invention. Figure 4 A specific embodiment of step S4300 is given. Step S4300 may include steps S4310 and S4320.

[0060] Step S4310: When the movable probe completes the scanning of the current local measurement area and the next local measurement area is within the current local scanning range, control the movable probe to complete the scanning of the current local scanning range.

[0061] This step embodies the core principle of "local scanning priority," which means utilizing the scanning capability of the movable probe in a stationary platform state to complete measurements of multiple local measurement areas as much as possible. After completing the scan of the current local measurement area, the spatial location information of the next local measurement area to be measured is immediately acquired and compared with the local scanning range of the current movable probe (e.g., the 80mm × 80mm area within the area array infrared interferometer where the movable probe can move). If the next local measurement area is completely within the local scanning range, it is determined that there is no need to drive the external moving platform 1; instead, the moving platform 1 remains stationary, and the movable probe is directly controlled to move from its current position to the starting point of the next local measurement area, executing the measurement task according to the pre-generated scanning path for that local measurement area.

[0062] This scheduling method relies on the internal movement capability of the movable probe. Because the movable probe has an independent two-axis motion mechanism within the area array infrared interferometer, it can move freely within an 80mm × 80mm range. When the distance between adjacent local measurement areas is less than this range (for example, local measurement area A and local measurement area B are adjacent, and the distance between the center of local measurement area B and the center of local measurement area A is less than 80mm), the movable probe can autonomously reach the next local measurement area without the assistance of the moving platform 1. During this step, the following operations are performed: First, the relative displacement between the current movable probe position and the starting point of the next local measurement area is calculated; second, the internal movement path of the movable probe is generated (usually using linear interpolation or rapid positioning); then, the movable probe is controlled to move to the new position and begin scanning. Throughout the entire process, the moving platform 1 remains stationary, avoiding the time overhead and vibration interference caused by starting and stopping the moving platform 1.

[0063] This significantly reduces the number of platform movements and shortens the measurement cycle. The internal movement speed of the movable probe is faster than that of the platform during large-scale movements, and there is no need for stabilization waiting time. Continuous local scanning can greatly save the overall measurement time. In addition, it can reduce vibration interference. Since the measurement environment is most stable when the platform is stationary, it is beneficial to ensure the repeatability and accuracy of local scanning data.

[0064] Step S4320: When the movable probe completes the scanning of the current local measurement area and the next local measurement area is outside the current local scanning range, control the moving platform 1 to move so that the movable probe enters the next local measurement area.

[0065] When the scanning capability of the movable probe reaches its limit, the external moving platform 1 takes over the task of moving across regions to ensure the continuity of the entire measurement. After the controller completes the scanning of the current local measurement area, if it determines that the next measurement area to be measured is beyond the local scanning range of the current movable probe (for example, the current probe has moved to the edge of its travel range, while the next measurement area is located further away), it determines that the local measurement area must be switched through the external moving platform 1.

[0066] Figure 5 This diagram illustrates a fourth embodiment of the dual-scan interferometry method for measuring the topography of a whole wafer provided by the present invention. Figure 5 A specific embodiment of step S5000 is given. Step S5000 may include steps S5100 and S5300.

[0067] Step S5100 obtains the positioning information of the mobile platform 1 corresponding to each local measurement area when the movable probe is in each local measurement area, as well as the pre-calibrated relative positional relationship between the mobile platform 1 and the movable probe in the coordinate system. It should be noted that the positioning information of the mobile platform 1 when the movable probe is in each local measurement area is the real-time recording of the absolute position coordinates of the mobile platform 1 in the global coordinate system during measurement in each local measurement area. It is important to emphasize that this positioning information is not the initial position before the measurement begins, but rather the actual position of the mobile platform 1 during measurement in each local measurement area. Since the mobile platform 1 will perform area-changing movement between different local measurement areas, the platform coordinates corresponding to each local measurement area are different. Therefore, it is necessary to record the platform position at the measurement time of each local measurement area separately and associate it with the scanning data of that local measurement area for storage.

[0068] The pre-calibrated relative positional relationship of the coordinate system can be measured and written once using a standard sample during the equipment's factory calibration or installation and commissioning phases. This relative positional relationship is usually stored in the form of a homogeneous transformation matrix. Alternatively, it can be the relative positional relationship between the two components recorded before the measurement begins.

[0069] Step S5200 transforms the scanning data of each local measurement area into the same global coordinate system based on the positioning information and the relative positional relationship of the coordinate system. The originally independent datasets scattered in each local measurement area are integrated into the same spatial reference system, and the data of adjacent local measurement areas are naturally connected in spatial position, providing a data foundation with consistent coordinates for subsequent stitching and fusion.

[0070] Step S5300 stitches together the scan data converted to the same global coordinate system to generate a full-wafer topography image. This step is the final integration stage of data processing, fusing the data from each measurement area, now unified to the global coordinate system, into a complete full-wafer topography image.

[0071] Figure 6 This diagram illustrates a fifth embodiment of the dual-layer scanning interferometry method for measuring the topography of a whole wafer provided by the present invention. Figure 6 A specific embodiment of step S5300 is given. Step S5300 may include steps S5310 and S5330.

[0072] Step S5310 determines the spatial overlap range between adjacent local survey areas based on the preset overlap amount and global coordinates. The spatial intersection area between adjacent local survey areas can be calculated based on the preset overlap amount and the global coordinate boundaries of each local survey area, determining which data points belong to the overlapping area.

[0073] Step S5320 fuses the two sets of scan data within the determined spatial overlap area. A preset fusion algorithm (such as weighted average, least squares fitting, or data optimization) is used to merge the two sets of data within the overlap area. Taking the weighted average method as an example, weights are assigned based on the distance of data points from the local survey area boundary (higher weight for the center, lower weight for the edge), and the weighted average is calculated as the final height value after fusion. Through fusion processing, redundant data within the overlap area is merged into a smooth, continuous set of data, eliminating the step effect at the splicing boundary.

[0074] Step S5330 stitches together all the fused scan data to generate a full wafer topography image.

[0075] After fusing all overlapping areas of adjacent local test zones, the data from each local test zone (original data is retained for non-overlapping areas, and fused data is used for overlapping areas) are combined into a complete 3D topography map using global coordinates. This topography map covers the entire test area of ​​the wafer, and each data point has unique global coordinates and height values. The controller can perform further post-processing on the full-wafer data, such as filtering and denoising, flatness calculation, warpage analysis, and 3D visualization rendering, and output the full-wafer topography map and related quality indicators (such as repeatability indicators and stitching error indicators) for use by operators or process systems.

[0076] Figure 7 This diagram illustrates a sixth embodiment of the dual-layer scanning interferometry method for measuring the topography of a whole wafer provided by the present invention. Step S5340 is included between steps S5330 and S5320, and steps S5350 and S5360 are included after step S5330.

[0077] Step S5340 calculates the stitching error of the two types of scan data within the spatial overlap area. After completing the deviation preprocessing and data fusion of the overlapping areas of adjacent local survey areas (or during the fusion process), residual statistical analysis is performed on the two sets of original scan data (i.e., data from two adjacent local survey areas before fusion) within the overlapping area. Two sets of height values ​​z1 and z2 corresponding to each coordinate point within the overlapping area are extracted, and the difference between them, Δz = z1 - z2, is calculated. Then, all differences within the entire overlapping area are statistically analyzed to obtain the stitching error index. For example, the maximum absolute error can be used as the stitching error, representing the most severe local deviation within the overlapping area, to identify extreme anomalies; alternatively, the average absolute deviation can be used to calculate the average level of deviation.

[0078] Step S5350 determines whether the stitching error exceeds a preset error threshold, obtaining a first judgment result. This judgment process can be performed independently for each stitching boundary between adjacent local test areas, rather than just evaluating the entire piece as a whole. This fine-grained quality monitoring enables precise location of problematic stitching positions, providing accurate anomaly location information for subsequent local retesting. Furthermore, multiple threshold levels (such as warning thresholds and action thresholds) can be set. When the stitching error exceeds the warning threshold but not the action threshold, a warning message can be recorded without triggering a retest, providing the user with a quality warning. The preset error threshold can be set in advance by the user.

[0079] Step S5360: When the first judgment result is yes, determine that the local measurement area corresponding to the scan data is an abnormal measurement area, and control the re-measurement of the abnormal measurement area.

[0080] In some implementations, when the difference between the stitching error and the preset error threshold is less than a first threshold, the overlap between the two local measurement areas corresponding to the stitching error is increased. The first threshold can be determined based on the measurement accuracy requirements. When the difference between the stitching error and the preset error threshold is less than the first threshold, it indicates that although the current quality is acceptable, it has entered the "warning zone." By increasing the overlap, the shared area between adjacent measurement areas is expanded, and the stitching algorithm can utilize more data points for deviation correction and fusion.

[0081] In a 6-inch wafer scenario, the central area of ​​the wafer to be inspected can be placed within the working area of ​​the area array infrared interferometer, and local measurements of the central area and its adjacent areas can be completed by a movable probe. Subsequently, the moving platform 1 moves the wafer to the remaining edge areas, allowing the movable probe to continue completing local measurements of the edge areas. By reducing unnecessary intermediate platform stops and repetitive positioning, the number of motion switching operations can be reduced.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer, characterized in that, include: Mobile platform; A wafer carrier, mounted on the mobile platform, is used to carry the wafer to be tested; An optical measurement device is disposed above the wafer carrier. The optical measurement device includes a movable probe and a reference mirror. The reference mirror and the measurement optical path of the movable probe together form an interferometric measurement reference. The movable probe is used to perform non-contact interferometric measurement on the surface of the wafer to be inspected. The controller is connected to both the mobile platform and the optical measurement device, and is configured to: Obtain the dimensions of the wafer to be inspected, as well as the local scanning range of the movable probe; Based on the size of the wafer to be inspected and the local scanning range, the wafer to be inspected is divided into several adjacent local measurement areas with a preset overlap. Based on the divided local measurement areas, the scanning path of the movable probe is generated; According to the division of each local measurement area, the mobile platform is controlled to move so that the movable probe enters each local measurement area in sequence. At the same time, according to the scanning path, after the movable probe completes the scanning of the current local measurement area, the mobile platform is controlled to move so that the movable probe enters the next local measurement area, until all local measurement areas have been scanned. The scanning data from each local measurement area are stitched together to generate a full wafer topography image.

2. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 1, characterized in that, The controller is also configured to: Based on the divided local test areas, the moving platform is controlled to move the wafer to be tested to a preset position corresponding to the corresponding local test area; When the wafer to be inspected moves to the preset position, the movable probe is controlled to complete the scanning of the current local measurement area according to the scanning path; When the current local measurement area is completed, the mobile platform is controlled to move so that the movable probe can enter the next local measurement area, until all local measurement areas are completed.

3. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 1, characterized in that, The controller is also configured to: When the movable probe completes the scanning of the current local measurement area and the next local measurement area is within the current local scanning range, the movable probe is controlled to complete the scanning of the current local scanning range. When the movable probe completes the scanning of the current local measurement area and the next local measurement area is outside the current local scanning range, the mobile platform is controlled to move so that the movable probe enters the next local measurement area.

4. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 1, characterized in that, The controller is also configured to: The positioning information of the mobile platform when the movable probe is in each local measurement area, and the pre-calibrated coordinate system relative position relationship between the mobile platform and the movable probe are obtained. Based on the positioning information and the relative positional relationship of the coordinate system, the scanning data of each local measurement area are converted to the same global coordinate system; The scan data, converted to the same global coordinate system, are stitched together to generate a full wafer topography image.

5. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 4, characterized in that, The step of stitching together the scan data transformed to the same global coordinate system to generate a full wafer topography image includes: Based on the preset overlap amount and global coordinates, determine the spatial overlap range between adjacent local survey areas; Fuse two sets of scan data within a defined spatial overlap range; The fused scan data are stitched together to generate a full wafer topography image.

6. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 5, characterized in that, After the step of fusing the two sets of scan data within the determined spatial overlap range and before the step of stitching together all the fused scan data to generate a full wafer topography image, the method further includes: Calculate the stitching error between the two scan data within the spatial overlap range; After the step of stitching together all the fused scan data to generate a full wafer topography image, the method further includes: Determine whether the suture error exceeds a preset error threshold to obtain a first determination result; If the first judgment result is yes, the local measurement area corresponding to the scan data is determined to be an abnormal measurement area, and the abnormal measurement area is remeasured.

7. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 6, characterized in that, The controller is also configured to: When the difference between the stitching error and the preset error threshold is less than the first threshold, the overlap between the two local measurement areas corresponding to the stitching error is increased.

8. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 1, characterized in that, The movable range of the movable probe corresponds to the local scanning range; And / or, The movable probe performs point-to-point movement via an encoder-driven mechanism.

9. The dual-layer scanning interferometry apparatus for measuring the morphology of a whole wafer as described in claim 1, characterized in that, The optical measuring device is a planar array infrared interferometer.

10. A two-layer scanning interferometry method for measuring the morphology of a whole wafer, characterized in that, include: Obtain the dimensions of the wafer to be inspected, as well as the local scanning range of the movable probe; Based on the size of the wafer to be inspected and the local scanning range, the wafer to be inspected is divided into several adjacent local measurement areas with a preset overlap. Based on the divided local test areas, a scanning path for the movable probe is generated; based on the scanning path, the moving platform used to carry the wafer to be tested is controlled to move so that the movable probe enters each local test area in sequence, and enters the next local test area after the movable probe completes the scanning of the current local test area, until all local test areas have been scanned. The scanning data from each local measurement area are stitched together to generate a full wafer topography image.

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