A correction device for wafer inspection

Abstract

Disclosed is a correction device for wafer detection, comprising a mounting base plate, a plurality of XYθ-axis guide modules, a driving device and a stage assembly, wherein the stage assembly is rotatably arranged on the mounting base plate, a plurality of XYθ-axis guide modules are arranged between the mounting base plate and the stage assembly and are evenly distributed on a circle where the rotation axis of the stage assembly is located, the XYθ-axis guide module comprises a guide module base plate, an X-axis guide module, a Y-axis guide module and a rotation module from bottom to top, the guide module base plate is fixed to the mounting base plate, the rotation module is fixedly connected to the stage assembly, and the driving device is connected to the X-axis guide module of one of the XYθ-axis guide modules to drive the stage assembly to rotate. The device can realize high-rigidity angle correction and zero-jitter detection.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer detection devices, and in particular to a correction device for wafer detection. Background Art

[0002] Wafer inspection includes detection of foreign matter, edge collapse, erosion, etc. In order to maximize the inspection efficiency and accuracy, it is necessary to ensure that the chips on the wafer can be imaged in the center of the microscope's field of view, that is, the grain direction must be consistent with the microscope inspection direction. However, the direction of the wafer when it is transferred to the inspection platform is inconsistent with the movement direction of the microscope. In order to ensure the efficiency and accuracy of the inspection, it is necessary to ensure that the wafer grain direction is consistent with the movement direction of the microscope during the inspection process. There are currently two main solutions:

[0003] 1. By adding a positioning camera, let the positioning camera take several pictures on the edge of the wafer, calculate the angle error between the wafer and the detection direction through the algorithm, control the movement of the X-axis and Y-axis on the stage, so that the grains in the same row on the wafer can pass through the center of the microscope field of view.

[0004] 2. Based on the previous solution, a direct-drive rotary servo motor is added under the detection platform. After calculating the angular error between the wafer and the detection direction, the servo motor is driven to rotate the corresponding angle to make the grain direction consistent with the movement direction of the microscope.

[0005] Although the above two solutions can meet the detection requirements, the first solution drives two axes to move at the same time, and the smoothness of multi-axis combined motion is not as good as that of single-axis motion, so the image quality is not as good as that of single-axis drive. The second solution uses a direct-drive servo motor. According to the characteristics of the servo motor, the motor will always vibrate slightly, affecting the image quality. Summary of the invention

[0006] In order to solve the technical problems in the prior art that the multi-axis combined motion is not smooth and the micro-jitter of the direct-drive servo motor affects the imaging quality, the present invention proposes a correction device for wafer inspection to solve the above-mentioned problems in the prior art.

[0007] The present invention proposes a correction device for wafer inspection, comprising a mounting base plate, a plurality of XYθ axis guide modules, a driving device and a stage assembly, the stage assembly is rotatably arranged on the mounting base plate, a plurality of XYθ axis guide modules are arranged between the mounting base plate and the stage assembly and are evenly distributed on the circle where the rotation axis of the stage assembly is located, the XYθ axis guide module comprises a guide module base plate, an X axis guide module, a Y axis guide module and a rotation module from bottom to top, the guide module base plate is fixed to the mounting base plate, the rotation module is fixedly connected to the stage assembly, and the driving device is connected to the X axis guide module of one of the XYθ axis guide modules to drive the stage assembly to rotate. The device drives the X axis guide module of one XYθ axis guide module to move through the driving device, because the XYθ axis guide module has three degrees of freedom in the X, Y and θ directions, and the remaining XYθ axis guide modules are subject to upper and lower fixed restrictions, and drive the stage assembly to rotate a certain angle smoothly with an ultra-high reduction ratio within its degree of freedom.

[0008] Preferably, the stage assembly is rotatably arranged on the mounting base plate through a rotating assembly, the rotating assembly includes a cross roller bearing and a rotating shaft, the outer ring of the cross roller bearing is fixed to the mounting base plate, and the two ends of the rotating shaft are respectively connected to the inner ring of the cross roller bearing and the lower end surface of the stage assembly. With this arrangement, the stage assembly can be rotatably arranged on the mounting base plate and a space for placing the XYθ axis guide module is formed between the two.

[0009] Further preferably, three XYθ axis guide modules are included, and the three XYθ axis guide modules are distributed on the mounting base plate and located at the points where the rotation axis of the stage assembly is divided into three equal parts. With this arrangement, the rotation of the stage assembly can be achieved more stably.

[0010] Preferably, the relationship between the relative movement amount δX of the X-axis guide module and the rotation angle δθ of the stage assembly is: δX=Rcos(δθ+θ)-R cosθ, where R represents the radius of the circle where the rotation axis of the XYθ axis guide module on the stage assembly is located, and θ represents the angle between the radius of the current position and the X-axis. This formula can be used to quickly calculate the relative movement amount of the X-axis guide module, thereby facilitating the control of the feed of the drive device to achieve precise angular rotation.

[0011] Further preferably, the driving device includes a motor and a ball screw mechanism, the motor drives the ball screw mechanism, the screw nut of the ball screw mechanism is arranged on a connecting seat, and the connecting seat is fixedly connected to the X-axis guide module. The motor and the ball screw mechanism can facilitate the control of the movement amount of the X-axis guide module.

[0012] Further preferably, the stage assembly includes a rotating shaft mounting plate, a horizontal adjustment mechanism and a vacuum adsorption platform, wherein the rotating shaft mounting plate is rotatably arranged on the mounting base plate through a rotating assembly, and the vacuum adsorption platform is arranged on the rotating shaft mounting plate through a plurality of horizontal adjustment mechanisms. With this arrangement, the horizontality of the vacuum adsorption platform can be adjusted.

[0013] Further preferably, at least three level adjustment mechanisms are included and are evenly arranged on the circle where the axis of the rotating shaft is located. Three points determine a plane, so the levelness of the vacuum adsorption platform can be adjusted by adjusting the three level adjustment mechanisms.

[0014] Preferably, the bottom plate of the guide module is provided with an X-axis guide part, and an X-axis guide track is correspondingly provided in the X-axis guide module. The X-axis guide module is also provided with a Y-axis guide part, and a Y-axis guide track is correspondingly provided in the Y-axis guide module. With this arrangement, two degrees of freedom in the X and Y directions of the guide module can be realized.

[0015] Further preferably, the rotating module is a bearing, the inner ring of the bearing is fixedly connected to the lower end surface of the stage assembly, and the outer ring is fixedly connected to the upper end surface of the Y-axis guide module. This arrangement enables the guide module to have a rotational degree of freedom on the basis of the two freedoms of X and Y.

[0016] Further preferably, the relative movement of the X-axis guide module δX=n×p, where n represents the number of turns of the screw and p represents the lead of the screw. This formula can be used to define the number of turns of the motor to control the relative movement of the X-axis guide module and thus control the rotation angle.

[0017] A correction device for wafer detection of the present invention uses a stepper motor to drive a ball screw to move linearly, and realizes the complex movement of a cam mechanism through X, Y, and θ combined guide rails to push the platform to perform rotational motion. Since the stepper motor can achieve zero jitter in a static state, it perfectly solves the jitter problem of a direct-drive servo motor. In addition, the linear motion is converted into rotational motion, and an ultra-high reduction ratio can be achieved, and the θ axis can be made very thin. In addition, the use of X, Y combined guide rails for guidance gives the platform ultra-high rigidity. Therefore, the angle correction problem and the jitter problem are solved, and high-quality microscopic detection can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the embodiments and are used together with the description to explain the principles of the present invention. It will be easy to recognize other embodiments and many expected advantages of the embodiments because they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale with each other. The same reference numerals refer to corresponding similar parts.

[0019] Figure 1 is an exploded diagram of a correction device for wafer inspection according to an embodiment of the present invention;

[0020] Figure 2 is a front view of a correction device for wafer inspection according to a specific embodiment of the present invention;

[0021] Figure 3 is an exploded view of an XYθ-axis guide module in a correction device for wafer inspection according to a specific embodiment of the present invention;

[0022] Figure 4 It is a structural schematic diagram of a driving device in a correction device for wafer inspection according to a specific embodiment of the present invention.

[0023] The meaning of the numbers in the figure: 1-module mounting base, 2-stepping motor, 3-ball screw mechanism, 31-stepping motor mounting seat, 32-coupling, 33-coupling fixing seat, 34-screw, 35-screw nut connecting seat, 4-XYθ axis guide module, 41-guide module base, 42-X axis guide part, 43, X axis guide module, 42'-Y axis guide part, 44-Y axis guide module, 45-rotation module, 5-cross roller bearing, 6-rotating shaft, 7-rotation axis mounting plate, 8-stage horizontal adjustment mechanism, 9-vacuum adsorption platform. DETAILED DESCRIPTION

[0024] In the following detailed description, reference is made to the accompanying drawings, which form a part of the detailed description and are shown by illustrative specific embodiments in which the present invention can be put into practice. To this end, directional terms, such as "top", "bottom", "left", "right", "up", "down", etc., are used with reference to the orientation of the figures described. Because the parts of the embodiments can be positioned in several different orientations, directional terms are used for the purpose of illustration and are by no means limiting. It should be understood that other embodiments may be utilized or logical changes may be made without departing from the scope of the present invention. Therefore, the following detailed description should not be adopted in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0025] Figure 1 FIG. 2 shows an exploded view of a correction device for wafer inspection according to an embodiment of the present invention. Figure 1As shown, the correction device for wafer inspection mainly includes a module mounting base plate 1, an XYθ axis guide module 4, a driving device and a stage assembly, wherein the driving device includes a stepping motor 2 and a ball screw mechanism 3, and the stage assembly includes a rotating shaft mounting plate 7, a stage horizontal adjustment mechanism 8 and a vacuum adsorption platform 9. The rotating shaft mounting plate 7 of the stage assembly is rotatably arranged on the module mounting base plate 1 around the rotating shaft 6 through the cross roller bearing 5 and the rotating shaft 6. The outer ring of the cross ball column bearing 5 is locked on the upper surface of the module mounting base plate 1, and the lower end surface of the rotating shaft 6 is locked on the inner ring of the cross ball column bearing 5. Since the cross roller bearing 5 and the rotating shaft 6 have a certain height, a space is formed between the rotating shaft mounting plate 7 and the module mounting base plate 1. The XYθ axis guide module 4 is installed in the space, and its bottom is fixedly connected to the module mounting base plate 1, and the top is connected to the rotating shaft mounting plate 7. The ball screw mechanism 3 of the driving device is connected to the XYθ axis guide module 4 to drive the X-axis module in the XYθ axis guide module 4 to move, so that The rotating axis mounting plate 7 is subjected to an X-axis force in the circumferential direction, and the rotating axis mounting plate 7 rotates under the restriction of the rotating shaft 6, and the XYθ axis guiding module 4 has three degrees of freedom of X-axis, Y-axis and θ, and its top is connected to the rotating axis mounting plate 7 for relative rotation. Therefore, when the X-axis is driven to displace, the Y-axis and θ will automatically adjust the displacement and rotation angle within the rotation radius of the rotating axis mounting plate 7 where the XYθ axis guiding module 4 is located, so that the rotating axis mounting plate 7 can complete the rotation smoothly, and because the process has a very high reduction ratio, the rotating axis mounting plate 7 (i.e., the stage assembly) is endowed with ultra-high rigidity, which can effectively avoid jitter during the process and achieve high-quality wafer detection.

[0026] In a specific embodiment, a plurality of XYθ axis guide modules 4 can be provided, and they are provided on a circle with the rotation axis of the rotation axis mounting plate 7 as the center. The radius of the circle is smaller than the radius of the rotation axis mounting plate 7 so that the XYθ axis guide module 4 can be fixed in the rotation axis mounting plate 7. Preferably, a plurality of XYθ axis guide modules 4 are evenly distributed on the circle in an equal manner. In this embodiment, three XYθ axis guide modules 4 are provided, and they are evenly distributed on the circle in a three-equal manner. One of the XYθ axis guide modules 4 is used as the active end, and the remaining XYθ axis guide modules 4 are used as the driven end. When the rotation axis mounting plate 7 rotates, the displacement or rotation angle of X, Y and θ is automatically adjusted according to the degree of freedom.

[0027] Combination Figure 2 , Figure 2 FIG. 4 shows a front view of a correction device for wafer inspection according to a specific embodiment of the present invention, as shown in FIG. Figure 2As shown, the ball screw mechanism 3 of the driving device is connected to one of the XYθ axis guide modules 4 to control its displacement in the X-axis direction, which promotes the X-axis displacement of the XYθ axis guide module 4 at the active end, thereby giving the rotating axis mounting plate 7 an X-axis thrust at the XYθ axis guide module 4 and its fixed part, so that the rotating mounting plate 7 rotates. Since the XYθ axis guide module 4 has three degrees of freedom of X-axis, Y-axis and θ, under the restriction of the degrees of freedom in the X and Y directions, a rotation trajectory on the radius where the fixed part is located can be formed, and then through the rotatable characteristics in the θ direction, it can be rotated while being fixed to the rotating axis mounting plate 7, avoiding the problem of being unable to rotate due to rigid connection.

[0028] In a specific embodiment, Figure 3 FIG. 4 shows an exploded view of an XYθ-axis guide module in a correction device for wafer inspection according to a specific embodiment of the present invention. Figure 3 As shown, the XYθ axis guide module 4 includes a guide module base 41, an X axis guide module 43, a Y axis guide module 44 and a rotation module 45 from bottom to top. The bottom of the guide module base 41 is fixed on the rotation axis mounting plate 7. The upper part of the guide module base 41 is provided with an X axis guide part 42, the bottom of the X axis guide module 43 is provided with a guide track corresponding to the X axis guide part 42, the upper part is provided with a Y axis guide part 42', the bottom of the Y axis guide module 44 is provided with a guide track corresponding to the Y axis guide part 42', and the rotation module 45 is a bearing, the outer ring of the bearing is fixed to the top of the Y axis guide module 44, the inner ring can rotate relative to the outer ring, and the inner ring is connected to the rotation axis mounting plate 7. There is a degree of freedom relationship between the X axis guide module 43, the Y axis guide module 44 and the rotation module 45 of the XYθ axis guide module, and the degree of freedom can be adjusted.

[0029] Figure 4 FIG. 1 is a schematic diagram showing the structure of a driving device in a correction device for wafer inspection according to a specific embodiment of the present invention. Figure 4 As shown, the stepper motor mounting seat 31 is arranged on one side of the coupling fixing seat 33 of the ball screw mechanism, and is fixed to the module mounting base 1 along with the coupling fixing seat 33. The stepper motor 2 is fixed on the stepper motor mounting seat 31, and is connected to the coupling 32 arranged in the coupling fixing seat 33, thereby driving the screw 34 connected to the coupling 32 to rotate. A screw nut is arranged on the screw 34, and the screw nut is fixed to the screw nut connecting seat 35. The rotation of the screw 34 can drive the overall displacement of the screw nut connecting seat 35.

[0030] In a specific embodiment, the screw nut connecting seat 35 is fixedly connected to the X-axis guide module 43 of the XYθ-axis guide module 4 to drive the X-axis guide module 43 to move. It should be recognized that the screw nut connecting seat 35 can also be fixedly connected to the Y-axis guide module 44, and the rotation of the rotating shaft mounting plate 7 can also be achieved by relying on the other two degrees of freedom.

[0031] In a specific embodiment, the vacuum adsorption platform 9 and the stage level adjustment mechanism 8 are installed on the shaft mounting plate 7, and the vacuum adsorption platform 9 is locked on the three support rods of the stage level adjustment mechanism 8; when the fine-thread nut on the stage level adjustment mechanism 8 is turned, the fine-thread nut will drive the support rod to extend and retract, and since three points determine a plane, the level of the vacuum adsorption platform 9 can be adjusted by simply turning the fine-thread nuts of the three stage level adjustment mechanisms 8. It should be recognized that the stage level adjustment mechanism 8 can also be set to be greater than 3 according to the size of the vacuum adsorption platform 9, and the technical effect of the present application can also be achieved.

[0032] In a specific embodiment, the wafer is transferred to the detection platform, and after the alignment camera takes several pictures on the edge of the wafer, the angle δθ between the wafer and the detection direction is calculated through a specific algorithm, and the movement amount of the lead screw nut (i.e., the displacement amount of the X-axis guide module of the XYθ axis guide module 4) δX and the rotation angle of the rotating platform conform to the following mathematical relationship: δX=R cos(δθ+θ)-R cosθ, where R represents the radius of the circle where the rotation axis of the XYθ axis guide module on the stage assembly is located, and θ represents the angle between the radius of the current position and the X-axis, which can be understood as the sum of the angular position θX of the center of the cross roller bearing connected to the X-axis and the workbench angle θ0 before the action. As long as the calculated angle δθ is substituted into the above formula, the relative movement amount of the X-axis, i.e., the movement amount of the lead screw nut, can be obtained. The relationship between the movement of the lead screw nut (i.e. the relative movement of the X axis) δX and the number of turns of the lead screw n is δX=n×p, where n represents the number of turns of the lead screw and p represents the lead of the lead screw. In this way, the detection platform can be controlled to rotate to a specific angle by controlling the rotation speed of the stepper motor.

[0033] This application is aimed at the problem that in the prior art, two axes are driven to move at the same time, and the smoothness of the multi-axis combined motion is not as good as that of the single-axis motion, so the image quality is not as good as that of the single-axis drive; a DD servo motor is used, and the characteristics of the servo motor will cause the motor to always slightly shake, affecting the image quality. A stepper motor is used to drive the ball screw to move linearly, and a complex motion similar to a cam mechanism is achieved through the X, Y combined guide rails and θ rotation to push the platform to perform rotational motion. Since the stepper motor can achieve zero jitter in a static state, the jitter problem of the DD servo motor is perfectly solved. In addition, the linear motion is converted into rotational motion, which can achieve an ultra-high reduction ratio, and the θ axis can be made very thin. In addition, the use of the X, Y combined guide rails as a guide gives the platform ultra-high rigidity. Therefore, the angle correction problem and the jitter problem are solved, and high-quality microscopic detection can be achieved.

[0034] Obviously, those skilled in the art can make various modifications and changes to the embodiments of the present invention without departing from the spirit and scope of the present invention. In this way, if these modifications and changes are within the scope of the claims of the present invention and their equivalents, the present invention is also intended to cover these modifications and changes. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are recorded in mutually different dependent claims does not indicate that the combination of these measures cannot be used to profit. Any reference numerals in the claims should not be considered to limit the scope.

Claims

1. A correction device for wafer inspection, characterized in that: It includes a mounting base plate, a plurality of XYθ-axis guide modules, a driving device and a stage assembly, wherein the stage assembly is rotatably arranged on the mounting base plate, a plurality of XYθ-axis guide modules are arranged between the mounting base plate and the stage assembly and are evenly distributed on the circle where the rotation axis of the stage assembly is located, the XYθ-axis guide module includes a guide module base plate, an X-axis guide module, a Y-axis guide module and a rotation module from bottom to top, the guide module base plate is fixed to the mounting base plate, the rotation module is fixedly connected to the stage assembly, one of the XYθ-axis guide modules is used as the active end, and the other XYθ-axis guide modules are used as the driven end, the driving device is connected to the X-axis guide module of the XYθ-axis guide module of the active end to drive the stage assembly to rotate; the stage assembly is rotatably arranged on the mounting base plate through the rotation assembly, The rotating assembly includes a cross roller bearing and a rotating shaft, the outer ring of the cross roller bearing is fixed to the mounting base plate, and the two ends of the rotating shaft are respectively connected to the inner ring of the cross roller bearing and the lower end surface of the stage assembly; the driving device includes a motor and a ball screw mechanism, the motor drives the ball screw mechanism, the screw nut of the ball screw mechanism is arranged on a connecting seat, and the connecting seat is fixedly connected to the X-axis guide module; the guide module bottom plate is provided with an X-axis guide part, and the X-axis guide module is correspondingly provided with an X-axis guide track, and the X-axis guide module is also provided with a Y-axis guide part, and the Y-axis guide module is correspondingly provided with a Y-axis guide track; the rotating module is a bearing, the inner ring of the bearing is fixedly connected to the lower end surface of the stage assembly, and the outer ring is fixedly connected to the upper end surface of the Y-axis guide module.

2. The correction device for wafer inspection according to claim 1, characterized in that: It comprises three XYθ axis guide modules, which are distributed on the mounting base plate and located at the points where the three equal parts of the circle where the rotation axis of the carrier assembly is located are divided.

3. The correction device for wafer inspection according to claim 1, characterized in that: The relationship between the relative movement amount δX of the X-axis guiding module and the rotation angle δθ of the stage assembly is: δX=R cos(δθ+θ)-R cosθ, wherein R represents the radius of the circle on which the rotation axis of the XYθ-axis guiding module is located on the stage assembly, and θ represents the angle between the radius of the current position and the X-axis.

4. The correction device for wafer inspection according to claim 1, characterized in that: The carrier assembly includes a rotating shaft mounting plate, a horizontal adjustment mechanism and a vacuum adsorption platform. The rotating shaft mounting plate is rotatably arranged on the mounting base plate through a rotating assembly, and the vacuum adsorption platform is arranged on the rotating shaft mounting plate through a plurality of horizontal adjustment mechanisms.

5. The correction device for wafer inspection according to claim 4, characterized in that: At least three of the horizontal adjustment mechanisms are included and are evenly distributed on the circle where the axis of the rotating shaft is located.

6. The correction device for wafer inspection according to claim 1, characterized in that: The relative movement amount of the X-axis guide module δX=n×p, wherein n represents the number of rotations of the screw rod, and p represents the lead of the screw rod.

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