Calibration system and calibration method

Abstract

The invention relates to a calibration system and a calibration method. In one aspect, there is provided a calibration system comprising: a movable table; the adjusting sheet is detachably arranged on the workbench, the adjusting sheet comprises a light sensing area and at least one light guide part, the light sensing area is located in the center of the adjusting sheet and used for interacting with light beams from the light source, and the light guide part extends from the light sensing area to the edge of the adjusting sheet; the at least one sensor is arranged outside the edge and is used for sensing the intensity of the light transmitted through the at least one light guide part; and a controller controlling the table to move along a first axis and along a second axis orthogonal to the first axis, and determining center coordinates of the first axis and the second axis based on a position of the table corresponding to a peak intensity of a signal received from the at least one sensor. Therefore, the precision of center positioning of the workbench can be improved, and the detection precision of the wafer can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor testing equipment technology, and more specifically, to calibration systems and calibration methods. Background Technology

[0002] In the manufacturing and inspection of semiconductor wafers, laser or infrared inspection equipment is typically used to scan and inspect the wafers. To ensure the accuracy of the inspection data, the center point of the wafer to be inspected needs to be aligned with the mechanical center (i.e., the origin of the coordinate system) of the worktable that supports the wafer, and this mechanical center must be aligned with the optical center (i.e., the axis of the laser or infrared beam) of the inspection equipment.

[0003] In related technologies, the calibration process to achieve such alignment often relies on manual or semi-automatic operation. These calibration methods are difficult to meet increasingly stringent testing accuracy requirements, which may affect the quality control of the final product. Summary of the Invention

[0004] This section is based on the general summary of this disclosure, and not on a full disclosure of the entire scope or all features of this disclosure.

[0005] According to one aspect of this disclosure, a calibration system is provided, comprising a movable stage, an adjustment plate, at least one sensor, and a controller. The adjustment plate is detachably disposed on the stage and includes a photosensitive area and at least one light guide. The photosensitive area is located at the center of the adjustment plate and is used to interact with a light beam from a light source. The at least one light guide extends from the photosensitive area toward an edge of the adjustment plate. The at least one sensor is disposed outside the edge of the adjustment plate and is used to sense the intensity of light transmitted via the at least one light guide. The controller is used to control movement of the stage along a first axis and along a second axis orthogonal to the first axis, and to determine the center coordinates of the first and second axes based on the position of the stage corresponding to the peak intensity of a signal received from the at least one sensor.

[0006] In some embodiments, at least one light guide may include a first light guide extending from the photosensitive area along a first axis and a second light guide extending from the photosensitive area along a second axis.

[0007] In some embodiments, the light guide can be a groove provided on the surface of the adjustment piece.

[0008] In some implementations, the photosensitive area may include a photosensitive head, which is in contact with one end of the light guide portion.

[0009] In some implementations, the controller can set the center coordinates of the first axis and the center coordinates of the second axis as the absolute zero point position of the stage relative to the light source.

[0010] In some embodiments, the calibration system may further include a clamping mechanism disposed on the worktable and used to clamp the adjustment piece, and a sensor may be disposed on the clamping mechanism.

[0011] In some embodiments, the worktable may include a first stage that moves along a first axis and a second stage disposed on the first stage and capable of moving along a second axis.

[0012] In some implementations, the controller can control the movement of the worktable when it receives a signal from at least one sensor.

[0013] In some implementations, the beam can be a laser beam or an infrared beam.

[0014] According to another aspect of this disclosure, a calibration method is also provided, the calibration method comprising: positioning an adjustment piece on a movable stage, the adjustment piece including a photosensitive area located at the center of the adjustment piece for interacting with a light beam from a light source, and at least one light guide extending from the photosensitive area toward an edge of the adjustment piece; driving the stage along a first axis and a second axis orthogonal to the first axis; sensing the intensity of light transmitted via the at least one light guide using at least one sensor located outside the edge of the adjustment piece; and determining the center coordinates of the first axis and the second axis based on the position of the stage corresponding to the peak intensity of a signal received from the at least one sensor.

[0015] According to the above technical solution, by setting adjustment plates and a controller to move the stage along two mutually orthogonal axes, the center coordinates of the stage can be calculated and determined based on peak intensity information. This transforms the problem of spatial positioning of the light source into determining the center position by moving along two axes and detecting the light intensity peaks in space. Therefore, automated and high-precision calibration of the stage's center position relative to the light source's beam center can be achieved, thereby improving the calibration accuracy of the calibration system and consequently improving the wafer inspection accuracy. Attached Figure Description

[0016] The features and advantages of embodiments of the present disclosure will become more readily understood from the following description with reference to the accompanying drawings. The drawings are not drawn to scale and some features may be enlarged or reduced to show details of specific components.

[0017] In the attached diagram: Figure 1 This is a schematic diagram illustrating calibration in related technologies.

[0018] Figure 2 This is a schematic diagram of a calibration system according to an embodiment of the present disclosure.

[0019] Figure 3This is a schematic diagram of a calibration system according to another embodiment of the present disclosure.

[0020] Figure 4 This is a schematic diagram of a calibration system according to yet another embodiment of the present disclosure.

[0021] Figure 5 This is a schematic diagram of a calibration system according to another embodiment of the present disclosure.

[0022] Figure 6 This is a schematic diagram of a calibration system according to yet another embodiment of the present disclosure.

[0023] Figure 7 This is a flowchart of a calibration method according to an embodiment of the present disclosure.

[0024] In the accompanying drawings, the same or corresponding technical features, parts or components are represented by the same or corresponding reference numerals. Detailed Implementation

[0025] The present disclosure will now be described in detail with reference to the accompanying drawings and exemplary embodiments. It should be noted that the following detailed description of the present disclosure is for illustrative purposes only and is not intended to limit the scope of the disclosure.

[0026] It should be noted that, for clarity, not all features of a particular embodiment are described or shown in the specification and drawings. Furthermore, to avoid unnecessary details obscuring the technical solutions of interest in this disclosure, only the device structures and parts closely related to the technical solutions of this disclosure are described and shown in the specification and drawings, while other details that are not closely related to the technical content of this disclosure and are known to those skilled in the art are omitted.

[0027] First, refer to Figure 1 It schematically illustrates the process of calibrating a workbench in related technologies.

[0028] The calibration device 100' is set on the worktable 200' to calibrate the center of the worktable 200'.

[0029] The calibration device 100' includes a perforated plate 120' and a light receiver 140'. The light receiver 140' is used to sense the light beam emitted from the light source S' (shown by dashed lines), and the perforated plate 120' has a through hole 122' at its center. During calibration, the worktable 200' is manually moved to find the position below the perforated plate 120' where the light receiver 140' senses the maximum light intensity as the center point. In other words, when the light beam emitted from the light source S' passes exactly through the through hole 122' at the center of the perforated plate 120', the light intensity sensed by the light receiver 140' is at its maximum, at which point the geometric center of the worktable 200' and the center of the light beam emitted by the light source S' can be determined, and the calibration is complete.

[0030] However, the accuracy of centering the stage 200' using this method is limited by the physical size of the holes. For example, the diameter of the central through-hole in the commonly used perforated plate 120' is 1mm, which is not very accurate. Furthermore, if the center of the stage is offset from the center of the beam emitted by the light source, it will cause the wafer inspection data to be inaccurate, thus affecting the quality of the wafer. Current calibration methods are difficult to achieve the precise adjustments required in the wafer inspection process.

[0031] Furthermore, since the workbench is usually enclosed inside the equipment, operators cannot visually observe the adjustment process in real time, and the judgment of the light intensity peak relies on indirect numerical readings. Therefore, calibration in this way is prone to subjective errors. Moreover, after each manual adjustment, a dummy wafer is usually inserted for testing. If the test data shows abnormalities, it indicates that the calibration was unsuccessful and the adjustment needs to be repeated, resulting in a time-consuming and inefficient calibration process.

[0032] In response, according to embodiments of this disclosure, a calibration system 100 is provided.

[0033] Below, refer to Figures 2 to 6 The calibration system 100 is described in detail.

[0034] First, such as Figure 2 As shown, the calibration system 100 includes a worktable 120, an adjustment plate 140, at least one sensor 160, and a controller 180.

[0035] The calibration system 100 can be integrated into, for example, a laser detection device or an infrared detection device, for automatically calibrating the center position of the worktable 120.

[0036] The stage 120 is used to hold the workpiece to be inspected (e.g., a wafer) or to hold the adjustment piece 140 during calibration, and the stage 120 is movable, for example, capable of precise movement along two mutually orthogonal axes within the calibration system 100. Figure 2As shown, the two mutually orthogonal axes can be a first axis (e.g., the X-axis) and a second axis (e.g., the Y-axis) along the horizontal plane of the worktable 120.

[0037] The adjustment plate 140 is detachably mounted on the worktable 120 and includes a photosensitive area 142 located at its geometric center and at least one light guide 144. The photosensitive area 142 is designed to interact with a light beam incident perpendicularly from the light source S, such that a portion of the light is captured and guided by the at least one light guide 144. Here, the at least one light guide 144 is designed to extend from the photosensitive area 142 toward the edge of the adjustment plate 140. This interaction can be, for example, absorption, reflection, scattering, or projection of light, or other forms are employed, without limitation. When the light beam illuminates the vicinity of the photosensitive area 142, a portion of the light is guided to the edge of the adjustment plate 140 via the light guide 144.

[0038] It is conceivable that the body of the adjustment piece 140 may be made of, for example, glass, quartz, or a metal or ceramic material with good dimensional stability. Furthermore, the adjustment piece 140 may be circular to allow it to be replaced with a workpiece (e.g., a wafer) of the same specifications for inspection operations.

[0039] At least one sensor 160 is disposed outside the edge of the adjustment piece 140 for sensing the intensity of light transmitted via at least one light guide portion 144 on the adjustment piece 140.

[0040] The controller 180 is electrically connected to the worktable 120 and the sensor 160 (shown in dashed lines) for receiving and processing light intensity signals from the sensor 160 in real time. The controller 180 is capable of controlling the movement of the worktable 120 along a first axis and along a second axis orthogonal to the first axis, and determining the center coordinates of the first axis and the second axis based on the position of the worktable 120 corresponding to the peak intensity of the signal received from at least one sensor 160.

[0041] In this way, by setting the adjustment plate 140 and causing the controller 180 to control the stage 120 to move along two mutually orthogonal axes, the center coordinates of the stage 120 are calculated and determined based on the processed light intensity signal (e.g., peak intensity information). Thus, the problem of spatial positioning of the light source is transformed into determining the center position by moving along two axial directions and detecting the light intensity peaks in space. This transforms the positioning reference from a vague bright spot into a clear, quantifiable signal peak, thereby improving the accuracy of center positioning of the stage 120 and consequently improving the wafer inspection precision.

[0042] It is conceivable that at least one light guide portion 144 may include a first light guide portion 1442 and a second light guide portion 1444.

[0043] like Figure 2 As shown, the first light guide 1442 extends from the photosensitive area 142 along a first axis (e.g., the X-axis) to one edge of the adjustment plate 140, and the second light guide 1444 extends from the photosensitive area 142 along a second axis (e.g., the Y-axis) to the other edge of the adjustment plate 140. When a light beam emitted by the light source S is incident on the photosensitive area 142, a portion of the light enters the first light guide 1442 and the second light guide 1444, and is guided to the edge of the adjustment plate 140 along the extending direction of each light guide 144.

[0044] Understandably, the number of light guides 144 can be adjusted according to the needs of the actual detection process. For example... Figure 3 As shown, the adjustment piece 140 includes light guiding portions 144 extending in multiple directions from the photosensitive area 142 toward its edge. Figure 3 The diagram schematically shows four light guide portions 144 spaced at 90° intervals and extending radially along the adjustment piece 140.

[0045] In this way, by setting multiple light guides 144 and corresponding sensors 160, at least two center coordinate information of the worktable 120 can be provided, thereby allowing the center coordinates of the worktable 120 to be determined more accurately based on multiple position calibration information. It is understood that by setting multiple light guides 144, the rotational error of the worktable 120 can also be calibrated to further improve the calibration accuracy of the calibration system 100.

[0046] It is conceivable that the light guide 144 can be a groove provided on the surface of the adjustment piece 140.

[0047] like Figure 4 As shown, the first groove 1442a and the second groove 1444a are orthogonally disposed on the surface of the adjustment piece 140 to allow the light beam emitted by the light source S to be confined and conducted within the groove. This groove structure can be formed, for example, by etching, laser engraving, or precision machining, and its inner wall can be polished or specially treated to enhance light transmission efficiency. It is conceivable that the geometry and size of the groove can be optimized according to the characteristics of the light beam emitted by the light source S and the receiving angle of the sensor 160; for example, the shape of the groove can be V-shaped, U-shaped, or rectangular, etc., without limitation.

[0048] In this way, by providing grooves with physical structures on the surface of the adjustment piece 140, a structurally stable adjustment piece 140 can be provided to improve the stability of positioning the stage 120 to the center position, thereby improving the wafer inspection accuracy.

[0049] It is understood that the light guiding portion 144 may also be a linear region with different optical reflectivity or transmittance formed on the surface of the adjustment piece 140 by printing, coating or material modification, so as to allow the light beam after interacting with the photosensitive area 142 to be guided to the sensor 160 at the edge of the adjustment piece 140. Exemplarily, the light guiding portion 144 may be a highly reflective metal wire, or an optical fiber embedded in the surface material of the adjustment piece 140, or other structures with light guiding properties, without limitation.

[0050] It is conceivable that the photosensitive area 142 may include a photosensitive head, which is in contact with one end of the light guiding part 144.

[0051] The photosensitive area 142 may include a photosensitive head. For example, the photosensitive head can directly contact one end of the light guide 144 to allow the light beam to be conducted through the light guide 144. It is understood that the photosensitive head can also be connected to the light guide 144 via a light guide connection device. Exemplarily, the photosensitive head can be a high-purity hemispherical quartz glass. After sensing an incident light beam, at least one light guide 144 in contact with it will conduct the light beam to the sensor 160. Furthermore, the hemispherical shape has light-concentrating properties, so that when the photosensitive area 144 detects light incident perpendicularly from the light source S, the light transmitted from the photosensitive area 144 to the at least one light guide 144 in contact with it is strongest, and the intensity of the light sensed by the sensor 160 is at its maximum. By setting the photosensitive head and having it contact the light guide 144, the light beam incident perpendicularly from the light source S can be more accurately and stably conducted through the light guide 144 to the sensor 160, thereby further improving the calibration accuracy of the calibration system 100.

[0052] It is conceivable that the controller 180 sets the center coordinates of the first axis and the center coordinates of the second axis as the absolute zero point position of the worktable 120 relative to the light source S.

[0053] It is understandable that by using the position of the worktable 120 corresponding to the peak intensity of the signal received by the sensor 160, the controller 180 can determine the center coordinate of the first axis as the zero position of the X-axis and the center coordinate of the second axis as the zero position of the Y-axis. After determining the new zero positions of the X-axis and Y-axis, the absolute center coordinates of the worktable 120 relative to the light beam emitted by the light source S are determined. These absolute center coordinates are the absolute zero position of the worktable 120 relative to the light source S.

[0054] In this way, the controller 180 controls the movement of the worktable 120 based on the preset absolute zero point position coordinates, so that the worktable 120 can move directly and accurately to the center position aligned with the light source S, thereby reducing the possibility of positional errors caused by multiple movements of the worktable 120 during the calibration process, and thereby improving the adjustment efficiency and accuracy of the calibration system 100.

[0055] It is conceivable that the calibration system 100 also includes a clamping mechanism 190, which is disposed on the worktable 120 and used to clamp the adjustment piece 140, and the sensor 160 is disposed on the clamping mechanism 190.

[0056] like Figure 5 As shown, the clamping mechanism 190 is disposed on the worktable 120 and is used to clamp the adjustment piece 140. For example, it can be disposed at the four corners or edges of the worktable 120. By setting the clamping mechanism 190 to fix the relative position of the adjustment piece 140 and the worktable 120, the stability of the relative position of the adjustment piece 140 and the worktable 120 during the movement of the worktable 120 can be improved, the positional deviation caused by relative displacement can be reduced, thereby improving the calibration accuracy of the calibration system 100, and thus improving the wafer detection accuracy.

[0057] When the clamping mechanism 190 retracts toward the center of the adjustment piece 140, it clamps the adjustment piece 140. When the clamping mechanism 190 expands outward in the opposite direction to the center of the adjustment piece 140, it allows the adjustment piece 140 to be unloaded from the calibration system 100 so that the adjustment piece 140 can be replaced with a wafer and a testing operation can be performed.

[0058] It is conceivable that sensor 160 is mounted on clamping mechanism 190.

[0059] like Figure 5 As shown, sensor 160 is integrated on clamping mechanism 190. For example, two sensors 160 can be provided. The first sensor 162 is provided on the edge of adjustment piece 140 along the first axis, and its photosensitive surface faces the first light guide part 1442. Correspondingly, the second sensor 164 is provided on the edge of adjustment piece 140 along the second axis, and its photosensitive surface faces the second light guide part 1444.

[0060] In this way, by using a non-contact optical sensing method, the possibility of interference with the light intensity signals received by the first sensor 162 and the second sensor 164 can be reduced, reducing wear and positioning errors caused by mechanical contact. Furthermore, by placing the sensor 160 on the clamping mechanism 190, the relative position of the sensor 160 and the light guide 144 can be adjusted more precisely, thereby improving the calibration accuracy and stability of the calibration system 100, and thus improving the detection accuracy of the wafer by the equipment after calibration by the calibration system 100.

[0061] It is conceivable that the worktable 120 includes a first platform 122 that moves along a first axis and a second platform 124 disposed on the first platform 122 and capable of moving along a second axis.

[0062] like Figure 6As shown, the worktable 120 includes a first platform 122 and a second platform 124 stacked vertically. The first platform 122 moves along a first axis (e.g., the X-axis), and the second platform 124 moves along a second axis (e.g., the Y-axis) perpendicular to the direction of movement of the first platform 122.

[0063] Exemplarily, a first stage 122 is mounted on a second stage 124 and is movable along a first axis (X-axis). Specifically, this movement can be achieved using an X-axis drive assembly including an X-axis motor 1222, an X-axis lead screw 1224, and an X-axis slide rail 1226. The X-axis motor 1222 (e.g., a stepper motor or a servo motor) drives the X-axis lead screw 1224 to rotate, thereby causing the first stage 122, connected to the lead screw nut, to perform a smooth linear movement along the X-axis slide rail 1226. Correspondingly, the second stage 124 is mounted on a stage base 130 and is movable along a second axis (Y-axis) orthogonal to the first axis (X-axis). Similarly, this movement can be achieved using a Y-axis drive assembly including a Y-axis motor 1242, a Y-axis lead screw 1244, and a Y-axis slide rail 1246.

[0064] Understandably, the platform base 130 can be made of a material with excellent dimensional stability, such as a marble platform, to ensure the long-term operational stability of the equipment and micron-level positioning accuracy. This material has an extremely low coefficient of thermal expansion, effectively resisting deformation caused by changes in ambient temperature and ensuring the stability of the coordinate system. For example, the marble platform can be 500mm * 500mm * 40mm in size to provide a stable reference for the entire calibration system 100.

[0065] In this way, through the coordinated movement of the first stage 122 and the second stage 124, the adjustment piece 140 set on the first stage 122 can reach any specified coordinate in the plane defined by the X-axis and Y-axis, and the movement of the worktable 120 in the X-direction and Y-direction is independent of each other, thereby further improving the calibration accuracy and stability of positioning the worktable 120 to the center position.

[0066] It is conceivable that the controller 180 can control the movement of the worktable 120 when it receives a signal from at least one sensor 160.

[0067] As previously described, the controller 180 determines the center coordinates of the first and second axes based on the position of the stage 120 corresponding to the peak intensity of the signal received from at least one sensor 160. In this case, the controller 180 can control the stage 120 to move based on the position of the axis direction corresponding to the peak value of the signal received by one of the sensors 160 when receiving a signal from that sensor 160. Correspondingly, the controller 180 can control the stage 120 to move only based on the axis direction corresponding to the respective sensor 160 when receiving a signal from any sensor 160. This simplifies the control algorithm and data processing of the controller 180, thereby improving the calibration speed of the calibration system 100.

[0068] It is conceivable that the beam could be a laser beam or an infrared beam.

[0069] Reference Figure 6 The light source S is used to emit a light beam (shown by dashed lines) onto the adjustment plate 140 for calibration operations. Exemplarily, the light source S can be a laser source or an infrared source inherent in the detection device, or the light source S can be set in the calibration system 100 to simulate a light beam.

[0070] According to another aspect of this disclosure, referring to Figure 7 It also provides a calibration method.

[0071] The calibration method includes: Step S701: Position the adjustment sheet on a movable worktable, wherein the adjustment sheet includes: a photosensitive area located at the center of the adjustment sheet and used to interact with a light beam from a light source; and at least one light guide extending from the photosensitive area toward the edge of the adjustment sheet. Step S702: Drive the worktable along the first axis and the second axis orthogonal to the first axis; Step S703: Sensing the intensity of light transmitted via at least one light guide using at least one sensor located outside the edge; and Step S704: Determine the center coordinates of the first axis and the second axis based on the position of the worktable corresponding to the peak intensity of the signal received from at least one sensor.

[0072] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the specific embodiments described and shown herein. Various changes to the exemplary embodiments can be made by those skilled in the art without departing from the scope defined by the claims of this disclosure.

[0073] The features mentioned and / or shown in the foregoing description of exemplary embodiments of this disclosure may be combined in the same or similar manner with one or more other embodiments, combined with features in other embodiments, or substituted for corresponding features in other embodiments. Such combinations or substitutions should also be considered as including within the scope of protection of this disclosure.

Claims

1. A calibration system, characterized in that, include: Movable workbench; An adjustment plate, detachably mounted on the worktable, includes: a photosensitive area located at the center of the adjustment plate and for interacting with a light beam from a light source; and at least one light guide extending from the photosensitive area toward an edge of the adjustment plate; and At least one sensor is disposed outside the edge to sense the intensity of light transmitted via the at least one light guide. The controller controls the movement of the worktable along a first axis and along a second axis orthogonal to the first axis, and determines the center coordinates of the first axis and the second axis based on the position of the worktable corresponding to the peak intensity of the signal received from the at least one sensor.

2. The calibration system according to claim 1, characterized in that, The at least one optical guide includes: A first light guiding portion extends from the photosensitive area along the first axis; and The second light guide extends from the photosensitive area along the second axis.

3. The calibration system according to claim 1, characterized in that, The light guiding part is a groove provided on the surface of the adjustment piece.

4. The calibration system according to claim 1, characterized in that, The photosensitive area includes a photosensitive head, which is in contact with one end of the light guiding portion.

5. The calibration system according to claim 1, characterized in that, The controller sets the center coordinates of the first axis and the center coordinates of the second axis as the absolute zero point position of the worktable relative to the light source.

6. The calibration system according to claim 1, characterized in that, It also includes a clamping mechanism disposed on the worktable and used to clamp the adjustment piece, and the sensor is disposed on the clamping mechanism.

7. The calibration system according to claim 1, characterized in that, The workbench includes: A first platform, capable of moving along the first axis; and A second platform is disposed on the first platform and is movable along the second axis.

8. The calibration system according to claim 1, characterized in that, When the controller receives a signal from the at least one sensor, it controls the worktable to move.

9. The calibration system according to claim 1, characterized in that, The beam is a laser beam or an infrared beam.

10. A calibration method, characterized in that, include: The adjustment plate is positioned on a movable worktable, wherein the adjustment plate includes: a photosensitive area located at the center of the adjustment plate and for interacting with a light beam from a light source; and at least one light guide extending from the photosensitive area toward the edge of the adjustment plate; The worktable is driven along a first axis and a second axis orthogonal to the first axis. The intensity of light transmitted via the at least one light guide is sensed using at least one sensor located outside the edge; and The center coordinates of the first axis and the second axis are determined based on the position of the worktable corresponding to the peak intensity of the signal received from the at least one sensor.

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