Wafer position detection method and detection system thereof

Abstract

The invention provides a wafer position detection method and a detection system thereof. The detection method comprises the following steps: acquiring surface topography information of a wafer edge area and a bearing table groove edge area at a plurality of acquisition positions along the circumference of a wafer; obtaining a two-dimensional surface topography curve of the edge of the wafer and the edge of the groove according to the surface topography information of each acquisition position; based on the two-dimensional surface topography curve, the relative position relation between the wafer edge and the groove edge is obtained. The system comprises corresponding function modules. According to the method, the two-dimensional surface topography curve is obtained by utilizing the edge surface topography information, and the edge is identified by analyzing the data of the curve instead of a traditional gray image, so that the industrial problem that a traditional visual system fails when the deep-color wafer is detected is effectively solved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor device inspection technology, and in particular to a method and system for detecting wafer position. Background Technology

[0002] In semiconductor manufacturing, precise wafer positioning is crucial for ensuring the accurate execution of subsequent processes such as photolithography, etching, and thin film deposition. Traditional wafer position detection typically relies on optical imaging-based vision systems, which identify wafer edges by capturing grayscale differences between the wafer and the stage, thereby determining its position.

[0003] However, this method has significant limitations when dealing with dark-colored wafers (such as silicon carbide (SiC) or certain specially treated silicon wafers), due to their low surface reflectivity and poor contrast with the background, leading to difficulties in image acquisition, decreased edge recognition accuracy, or even complete failure. Furthermore, changes in ambient lighting, lens contamination, or reflections can easily interfere with image quality, further affecting detection reliability.

[0004] Therefore, existing visual inspection technologies are insufficient to meet the requirements for high-precision and high-stability wafer positioning, especially given the widespread application of advanced processes and new materials, which exacerbates this problem. Summary of the Invention

[0005] In view of the above problems, the purpose of this disclosure is to provide a wafer position detection method and system to overcome the limitations of traditional visual inspection methods in low-reflectivity wafer application scenarios, and to achieve high-precision and high-stability position detection for different types of wafers, especially dark wafers.

[0006] According to one aspect of the embodiments of this disclosure, a method for detecting wafer position is provided, comprising:

[0007] Surface morphology information of the wafer edge region and the bearing stage groove edge region is acquired at multiple acquisition locations along the wafer circumference;

[0008] Two-dimensional surface morphology curves of the wafer edge and the groove edge are obtained based on the surface morphology information at each acquisition location;

[0009] Based on the two-dimensional surface topography curve, the relative positional relationship between the wafer edge and the groove edge is obtained.

[0010] Optionally, the two-dimensional surface topography curve includes the height values ​​of the wafer edge and the groove edge.

[0011] Optionally, obtaining the relative positional relationship between the wafer edge and the groove edge includes:

[0012] Based on the height value, the wafer edge feature points and groove edge feature points where the height changes abruptly in the two-dimensional surface topography curve are obtained, and the geometric distance between the two feature points is obtained.

[0013] Optionally, the plurality of data collection locations shall be at least three.

[0014] The detection method further includes: determining whether the difference between the plurality of geometric distances is within a preset range; if the determination result is yes, then the wafer position deviates from the target position; if the determination result is yes, then the wafer position is at the target position.

[0015] Alternatively, determine whether the difference between multiple geometric distances and the standard value is within a preset range. If the determination result is yes, then the wafer position deviates from the target position. If the determination result is yes, then the wafer position is located at the target position.

[0016] Optionally, the plurality of data collection locations may be two.

[0017] The detection method further includes: determining whether the difference between the two geometric distances and the standard value is within a preset range; if the determination result is yes, then the wafer position deviates from the target position; if the determination result is yes, then the wafer position is located at the target position.

[0018] Optionally, obtaining the relative positional relationship between the wafer edge and the groove edge includes determining the height difference between the upper surface of the wafer and the support stage surface based on the height value.

[0019] The height difference is used to determine whether the wafer is placed flat.

[0020] Optionally, the detection results and detection data of the detection method are used to adjust the placement orientation of the wafer and / or optimize the motion trajectory.

[0021] According to another aspect of the embodiments of this disclosure, a wafer position detection system is provided for implementing the detection method described above, the detection system comprising:

[0022] Multiple measuring devices are used to collect surface topography information of the wafer edge region and the bearing stage groove edge region at multiple acquisition positions along the wafer circumference;

[0023] The data processing module is used to obtain two-dimensional surface morphology curves of the wafer edge and the groove edge based on the surface morphology information at each acquisition location, and to obtain the relative positional relationship between the wafer edge and the groove edge based on the reconstructed two-dimensional surface morphology curves.

[0024] Optionally, at least three of the measuring devices are arranged around the groove.

[0025] Optionally, two measuring devices may be provided on the circumference of the groove or on the concentric circumference of the groove.

[0026] One of the above technical solutions has the following beneficial effects:

[0027] By acquiring surface topography information of the wafer edge region and the substrate groove edge region, and reconstructing a two-dimensional surface topography curve based on this information, the relative positional relationship between the wafer and the groove can be analyzed. This method abandons the traditional visual detection mode that relies on image grayscale contrast, and instead uses the height or topography changes of the physical surface as the judgment criterion, significantly improving the detection reliability in low reflectivity, dark wafer (such as SiC wafer) scenarios, and solving the long-standing technical problem in the industry of edge recognition failure due to imaging difficulties.

[0028] The reconstructed 2D surface topography curves include height values, allowing detection to extend beyond planar contour recognition and incorporate topographic features in the vertical direction. This improvement enhances data dimensionality, increases the accuracy and robustness of edge localization, and ensures stable extraction of effective features, especially in environments with slight contamination, reflections, or shadows, thereby improving system robustness.

[0029] Feature points at wafer edges and groove edges are identified by analyzing abrupt changes in height values, and the geometric distance between them is calculated. Since there is usually a significant step change in height between wafer edges and stage groove edges, this abrupt change feature can be used to improve edge positioning accuracy, avoiding misjudgments caused by blurred edges or gentle gradients in image processing, and significantly improving detection resolution.

[0030] By employing at least three measuring devices surrounding the groove, multiple geometric distances are acquired, and the wafer's position is determined by comparing the differences between these distances or their deviations from standard values. This multi-point collaborative detection mechanism effectively identifies non-ideal placement states of the wafer, such as eccentricity or tilt, enabling comprehensive position assessment and ensuring that the wafer's orientation in the horizontal plane meets process requirements. This provides a reliable basis for automatic alignment and precise clamping.

[0031] Two measuring devices are set on the circumference of the groove or its concentric circumference. By acquiring the geometric distance in two directions and performing deviation analysis, the wafer position can be quickly determined. This scheme reduces system complexity and cost while ensuring basic positioning functions. It not only meets the requirements for detection accuracy but also increases detection efficiency and economy, demonstrating good engineering applicability.

[0032] The height difference between the upper surface of the wafer and the stage surface is obtained by measuring the height value to determine whether the wafer is placed flat. This function can effectively detect problems such as wafer warping, partial suspension, or foreign object clamping, preventing defects such as uneven heat conduction, defocusing during exposure, or inconsistent film thickness in subsequent processes caused by uneven placement, thus helping to improve process yield and equipment safety.

[0033] The aforementioned detection results can be used to adjust the wafer placement posture or optimize the motion trajectory, demonstrating the high integration and closed-loop control potential of this method. The detection data can be fed back to the robot or stage control system in real time, enabling automatic correction, dynamic compensation, or path optimization, significantly improving the automation level, operational efficiency, and process consistency of the semiconductor manufacturing process.

[0034] It should be noted that the above general description and the following detailed description are exemplary and explanatory only and do not limit this disclosure. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only involve some embodiments of this disclosure, and are not intended to limit this disclosure.

[0036] Figure 1 A schematic diagram of the structure of a wafer processing system according to an embodiment of the present disclosure is shown;

[0037] Figure 2 A flowchart of a wafer position detection method according to an embodiment of the present disclosure is shown;

[0038] Figure 3 A schematic diagram of the detection principle of the first embodiment of this disclosure is shown;

[0039] Figure 4 It shows Figure 3 Two-dimensional surface morphology curves corresponding to each acquisition location;

[0040] Figure 5 A schematic diagram of the detection principle of the second embodiment of this disclosure is shown;

[0041] Figure 6 It shows Figure 5 Two-dimensional surface morphology curves corresponding to each acquisition location;

[0042] Figure 7 A schematic diagram of the structure of a wafer position detection system according to an embodiment of the present disclosure is shown;

[0043] Figure 8 This diagram shows a partial structural schematic of the process chamber in a wafer processing system.

[0044] Figure 9A schematic diagram showing the position of the measuring device in another embodiment of the detection system is shown. Detailed Implementation

[0045] The wafer position detection method and system of this disclosure will be described in detail below with reference to the accompanying drawings to fully reveal its technical implementation path and ensure consistency with the claims and the invention content. In the drawings, the same or similar structures are represented by the same reference numerals. For ease of understanding, the drawings are not drawn to scale, and some well-known structures may be omitted. It should be understood that the scope of protection of this disclosure is not limited to the specific embodiments described below, and those skilled in the art can make reasonable changes and combinations without departing from the spirit of this disclosure.

[0046] The wafer position detection method disclosed herein aims to solve the problem of traditional grayscale image-based visual detection failing in dark wafer scenes. For example... Figure 1 As shown, this method can be integrated into a semiconductor wafer processing system, which includes components such as a front-opening unified pod (FOUP) 10, an operating table 20, robotic arms 31 and 32, a wafer inspection module 40, a locking unit 50, a loading chamber 61, an unloading chamber 62, a transfer chamber 70, and a process chamber 80. The robotic arm 32 is responsible for transferring the wafer from the loading chamber 61 to the carrier stage within the process chamber 80 for processing. To ensure process accuracy, the wafer 100 must be accurately placed in the center region of the groove 82 of the carrier stage 81 and maintained in a horizontal position. Therefore, this disclosure proposes a non-image-based detection method based on surface topography information to achieve high-precision and robust determination of the wafer position.

[0047] Figure 2 A flowchart of a wafer position detection method according to an embodiment of the present disclosure is shown. Figure 3 A schematic diagram of the detection principle of the first embodiment of this disclosure is shown. Figure 4 It shows Figure 3 Two-dimensional surface topography curves corresponding to each acquisition location are shown below. Figures 2 to 4 The detection method of the first embodiment of this disclosure will be described in detail.

[0048] In step S01, surface topography information of the edge region of wafer 100 and the edge region of groove 82 of support stage 81 is acquired at multiple acquisition positions along the circumference of wafer 100.

[0049] like Figure 3As shown, this embodiment has three acquisition positions, each corresponding to a dashed box. The edges of wafer 100 and groove 82 within different acquisition positions are scanned to acquire a series of discrete three-dimensional coordinate data points (X, Y, Z), which are also referred to as surface topography information. The scanning device in this step can be, for example, a confocal displacement sensor or a white light interferometer.

[0050] However, the embodiments disclosed herein are not limited thereto, and those skilled in the art can make other settings for the number of collection locations as needed, such as four or more.

[0051] In step S02, two-dimensional surface morphology curves of the edge of wafer 100 and the edge of groove 82 are obtained based on the surface morphology information of each acquisition location.

[0052] In this step, for example, the acquired three-dimensional coordinate data points are first filtered to remove environmental noise and random fluctuations. Then, an interpolation algorithm is used to reconstruct the discrete points into a continuous two-dimensional surface topography curve, such as... Figure 4 As shown, the two-dimensional surface topography curve uses the horizontal axis to represent spatial position and the vertical axis to represent the height value of the corresponding point, clearly reflecting the height changes between the upper surface of wafer 100, the edge of wafer 100, the edge of groove 82, and the platform surface of support stage 81. The device that converts the three-dimensional coordinate data points into two-dimensional surface topography curves in this step is, for example, a data processing module such as a host computer, a slave computer, or a programmable logic controller.

[0053] In step S03, the relative positional relationship between the edge of wafer 100 and the edge of groove 82 is obtained based on the two-dimensional surface topography curve. This relative positional relationship includes the actual distance between the edge of wafer 100 and the edge of groove 82, or the geometric distance mapped onto the two-dimensional surface topography curve. This step can be implemented through a data processing module.

[0054] like Figure 4 As shown, due to the significant height variations in the physical structure of the edges of wafer 100 and groove 82, the two-dimensional surface morphology curves at each acquisition location exhibit significant height abrupt changes at the corresponding positions. By performing differential analysis or threshold detection on the curves, feature points exhibiting abrupt height changes were identified, namely feature points A1, A2, and A3 on the edge of wafer 100 and feature points B1, B2, and B3 on the edge of groove 82. The geometric distances d1 between points A1 and B1, d2 between points A2 and B2, and d3 between points A3 and B3 were then obtained. Combined with... Figure 3 and Figure 4 Geometric distance d1 corresponds to actual distance D1, geometric distance d2 corresponds to actual distance D2, and geometric distance d3 corresponds to actual distance D3. In this embodiment, the actual distance and geometric distance are mapped in a 1:1 ratio.

[0055] Understandably, after obtaining geometric distances d1 to d3, it is determined whether the difference between these three geometric distances is within a preset range. If the result is yes, the wafer position deviates from the target position; if the result is yes, the wafer position is at the target position. In an optional embodiment, the target position is the position where wafer 100 is centered in the groove 82. Taking a wafer 100 size of 300 mm (12 inches) as an example, the preset range is set to within ±5 mm. When the differences between geometric distances d1 and d2, d2 and d3, and d3 and d1 are all within ±5 mm, it is determined that wafer 100 is centered. If the difference of any set of data is outside ±5 mm, it is determined that wafer 100 deviates from the target position. Of course, those skilled in the art can make other settings for the preset range corresponding to wafers of different sizes as needed. In addition, if the actual distance and the geometric distance are not mapped 1:1, the preset range can also be transformed proportionally.

[0056] In some other embodiments, the geometric distances d1, d2, and d3 can be compared with standard values. If all deviations are within a preset range, the wafer 100 is determined to be located at the target position. For example, a test wafer is placed in the groove 82, and the test wafer is positioned at the target position, taking centering as an example. The geometric distance obtained from the two-dimensional surface morphology curve of the edge of the test wafer and the edge of the groove is recorded as the standard value, and used as the comparison basis for subsequent measurements.

[0057] Understandably, the height difference between the upper surface of wafer 100 and the mesa surface of the support stage 81 can also be obtained from the height value in the two-dimensional surface topography curve. This height difference is used to determine whether wafer 100 is completely aligned with the bottom of the groove 82 and placed flat. For example, if the height difference is greater than 5 mm, it may mean that wafer 100 is warped, has particulate contamination, or is not fully positioned.

[0058] Figure 5 A schematic diagram of the detection principle of the second embodiment of this disclosure is shown. Figure 6 It shows Figure 5 Two-dimensional surface morphology curves corresponding to each acquisition location.

[0059] The following will combine Figure 5 and Figure 6 The detection method of the second embodiment of this disclosure will be described in detail, wherein the similarities with the first embodiment will not be repeated here.

[0060] The difference is that, for example Figure 5 As shown, this embodiment has two acquisition locations, each corresponding to a dashed box. The edges of wafer 100 and groove 82 within different acquisition locations are scanned to acquire surface topography information.

[0061] like Figure 6As shown, by performing differential analysis or threshold detection on the two-dimensional surface topography curve, feature points with abrupt height changes are identified, namely feature points A4 and A5 on the edge of wafer 100 and feature points B4 and B5 on the edge of groove 82. The geometric distance d4 between points A4 and B4, and the geometric distance d5 between points A5 and B5 are then obtained. Combined with... Figure 5 and Figure 6 The geometric distance d4 corresponds to the actual distance D4, and the geometric distance d5 corresponds to the actual distance D5. The geometric distances d4 and d5 are compared with the standard values ​​respectively. If all deviations are within the preset range, the wafer is determined to be located at the target position.

[0062] Figure 7 The diagram below shows a schematic representation of a wafer position detection system according to an embodiment of the present disclosure. Figure 8 This diagram shows a partial structural schematic of the process chamber in a wafer processing system. The positional relationship between the measuring device and the stage is shown to clearly illustrate this. Figure 7 The transparent cover has been omitted.

[0063] like Figure 7 As shown, this disclosure provides a wafer position detection system. The core components of this detection system include multiple measuring devices 210 and a data processing module 220. The multiple measuring devices 210 are used to perform the tasks described above for acquiring surface topography information, while the data processing module 220 is used to perform the tasks described above for establishing a two-dimensional surface topography curve, obtaining the relative positional relationship between the edge of the wafer 100 and the edge of the groove 82, determining whether the position of the wafer 100 deviates from the target position, and determining whether the wafer 100 is completely flush with the bottom of the groove 82.

[0064] The measuring device 210 is, for example, a confocal displacement sensor or a white light interferometer, which is mounted on such a device as... Figure 8 Near the transparent cover plate 83 at the top of the process chamber shown, the light path points downwards towards the location of the groove 82. This type of sensor can accurately obtain the height (Z-axis) information of the measured point by projecting a focused light spot and receiving the reflected signal. Moreover, its measurement results do not depend on the color or reflectivity characteristics of the measured surface, making it particularly suitable for the detection of dark, low-reflectivity wafer materials such as silicon carbide (SiC).

[0065] In this embodiment, it can be understood that three measuring devices 210 are provided around the groove 82. Of course, four or more can also be provided as needed.

[0066] The data processing module 220 can obtain detection results and data, which can also be used to adjust the placement posture of wafer 100 and / or optimize the motion trajectory. In this embodiment, the control module 230 of the wafer processing system receives the results output by the data processing module 220 and, combined with the standard motion trajectory of the robotic arm 32, generates correction parameters for adjusting the placement posture of wafer 100 or optimizing the motion trajectory. If an overall offset of wafer 100 is detected, the system can automatically compensate for the pick-up and place coordinates of the robotic arm 32. For example, if the wafer center offset is measured to be +0.8mm, the robotic arm 32 will first lift 5mm, then translate -0.8mm, and finally lower it again to complete the compensation, so that the wafer is centered. If wafer 100 is found to be tilted, the attitude angle of the end effector can be adjusted to achieve stable placement. This function significantly improves the automation level of the equipment and the consistency of the process.

[0067] Figure 9 A schematic diagram showing the position of the measuring device in another embodiment of the detection system is shown.

[0068] like Figure 9 As shown, in another embodiment, the detection system provides two measuring devices 210 on the circumference of the groove 82 or on its concentric circumference.

[0069] Combination Figure 5 and Figure 6 During system initialization or calibration, a standard-sized test wafer is precisely centered within the groove 82, with the wafer center coinciding with the groove center O. Two measuring devices 210 collect surface topography information at corresponding locations and, by analyzing the two-dimensional surface topography curves, identify the height abrupt change points between the wafer edge and the groove edge, calculating the standard value d0 for this state. This standard value d0 is recorded and stored in the data processing module 220 as a standard reference for subsequent testing.

[0070] In the actual testing process, after the wafer 100 to be tested is placed in the groove 82, the two measuring devices 210 simultaneously acquire the current geometric distances d4 and d5. Since the center position of the groove 82 is known and fixed, and ideally the wafer 100 should be coaxial with the groove 82, the theoretical position of the edge of the wafer 100 is uniquely determined by its center and standard radius.

[0071] According to the principles of plane geometry: within a circular region with a known center, if the distance measured along either of two different directions deviates from the standard value d0, it can be determined that the center of the measured circle (wafer) has shifted. In other words, the two measurement points, combined with the known center, constitute a geometric constraint on the position of the wafer's center. Only when the wafer's center coincides with the center of the groove will the geometric distances in both directions simultaneously equal the standard value d0.

[0072] Therefore, the data processing module 220 determines the wafer position by comparing the deviations of d4 and d0, and d5 and d0, to see if they are all within a preset range. Taking a wafer 100 with a size of 300 mm (12 inches) as an example, the preset range is set to within ±5 mm. If any deviation exceeds the preset range, it can be determined that the wafer is not in the target position and there is a deviation.

[0073] This embodiment achieves effective wafer position determination using only two measuring devices 210, significantly reducing system cost and data processing complexity. Furthermore, since the determination is based on the height variation of the physical morphology rather than image grayscale, it remains effective for detecting dark-colored, low-reflectivity wafers. This embodiment achieves efficient and reliable wafer centering through a geometric constraint mechanism, fully demonstrating its technological value and practicality.

[0074] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for detecting wafer position, comprising: Surface morphology information of the wafer edge region and the bearing stage groove edge region is acquired at multiple acquisition locations along the wafer circumference; Two-dimensional surface morphology curves of the wafer edge and the groove edge are obtained based on the surface morphology information at each acquisition location; Based on the two-dimensional surface topography curve, the relative positional relationship between the wafer edge and the groove edge is obtained.

2. The detection method according to claim 1, wherein, The two-dimensional surface topography curve includes the height values ​​of the wafer edge and the groove edge.

3. The detection method according to claim 2, wherein, Obtaining the relative positional relationship between the wafer edge and the groove edge includes: Based on the height value, the wafer edge feature points and groove edge feature points where the height changes abruptly in the two-dimensional surface topography curve are obtained, and the geometric distance between the two feature points is obtained.

4. The detection method according to claim 3, wherein, The number of data collection locations is at least three. The detection method further includes: determining whether the difference between the plurality of geometric distances is within a preset range; if the determination result is yes, then the wafer position deviates from the target position; if the determination result is yes, then the wafer position is at the target position. Alternatively, determine whether the difference between multiple geometric distances and the standard value is within a preset range. If the determination result is yes, then the wafer position deviates from the target position. If the determination result is yes, then the wafer position is located at the target position.

5. The detection method according to claim 3, wherein, The multiple data collection locations are two in number. The detection method further includes: determining whether the difference between the two geometric distances and the standard value is within a preset range; if the determination result is yes, then the wafer position deviates from the target position; if the determination result is yes, then the wafer position is located at the target position.

6. The detection method according to claim 2 further includes obtaining the height difference between the upper surface of the wafer and the stage surface based on the height value. in, The height difference is used to determine whether the wafer is placed flat.

7. The detection method according to any one of claims 1 to 6, wherein, The detection results and data from the detection method are used to adjust the placement orientation of the wafer and / or optimize the motion trajectory.

8. A wafer position detection system for implementing the detection method according to any one of claims 1 to 7, the detection system comprising: Multiple measuring devices are used to collect surface topography information of the wafer edge region and the bearing stage groove edge region at multiple acquisition positions along the wafer circumference; The data processing module is used to obtain two-dimensional surface morphology curves of the wafer edge and the groove edge based on the surface morphology information at each acquisition location, and to obtain the relative positional relationship between the wafer edge and the groove edge based on the reconstructed two-dimensional surface morphology curves.

9. The detection system according to claim 8, wherein, At least three of the measuring devices are arranged around the groove.

10. The detection system according to claim 8, wherein, Two measuring devices are provided on the circumference of the groove or on the concentric circumference of the groove.

Images