Wafer detection point spiral scanning motion device and method

Abstract

The invention belongs to the technical field of wafer automatic detection equipment, and provides a wafer detection point spiral scanning motion device and method in order to solve the problems that linear scanning detection coverage of an existing wafer is uneven, a detection blind area is likely to be generated, and repeated scanning is needed to affect the detection efficiency. The equidistant spiral track movement of the wafer in the plane is completed through the rotating platform and the two transfer platforms, the optical detection module collects spectral information at a fixed position at a preset frequency in the moving process, the whole surface of the wafer is uniformly covered from the center to the edge, no detection blind area is ensured, overlapping or omission in the detection process is effectively reduced, and the detection efficiency is improved. The linear speed is kept at a constant speed, so that re-collection and missing collection of collection points are avoided, point spiral scanning detection in the radial plane of the wafer is completed, the detection device does not need to be started and stopped frequently, the detection speed is adjustable, and the detection efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer automatic detection equipment, and in particular relates to a wafer detection point spiral scanning motion device and method. Background Art

[0002] With the advancement of semiconductor technology, the requirements for detection accuracy and efficiency are increasing, and the development of automated and high-precision detection technology has become an urgent need. Therefore, it is necessary to continuously explore and innovate to improve the automation, accuracy and performance of silicon wafer detection technology to meet the high quality and high efficiency requirements of the semiconductor manufacturing industry.

[0003] In the field of semiconductor manufacturing, silicon wafers are the basic materials for the production of integrated circuits. Their quality and performance have a decisive influence on the reliability and stability of the final product. Silicon wafers undergo multiple processes during the manufacturing process, which may leave various defects on their surfaces, such as scratches and water stains. The presence of these defects will not only reduce the performance of silicon wafers, but may also seriously affect their yield rate. Therefore, accurate and comprehensive inspection of silicon wafers is a key link in ensuring the quality of semiconductor devices. The choice of scanning method directly affects the accuracy and efficiency of detection. The common traditional scanning method now is linear scanning, which actually has obvious disadvantages in practical applications. First, the problem of uneven coverage of linear scanning is prominent. Due to the limitation of the scanning path, it is easy to produce detection blind spots in certain areas of the wafer, and it is impossible to achieve full coverage. Secondly, linear scanning often requires repeated scanning many times, which not only increases the detection time, but also reduces the detection efficiency. In addition, linear scanning requires frequent pauses and changes in direction, which also has a certain impact on the stability and detection accuracy of the system. Summary of the invention

[0004] In view of the problems existing in the prior art, a point spiral scanning wafer detection device and method are provided. The present invention controls the linear speed in the axis direction and the angular velocity of the precision rotating platform so that the path of the camera scanning the wafer is an equidistant spiral line, while ensuring that the optical detection module collects spectral data at a preset frequency to meet the uniformity of the sampling points. The present invention does not need to frequently start and stop the detection device, and the linear velocity and angular velocity during movement can be adjusted according to the detection requirements. Therefore, the inertial impact is small and the adaptability is good, which can effectively improve the wafer detection accuracy and efficiency.

[0005] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0006] A spiral scanning motion device for wafer inspection points, comprising a precision rotating platform for adsorbing, fixing and rotating wafers, and two transfer platforms for moving wafers, the moving directions of the two transfer platforms being perpendicular to each other, the precision rotating platform being placed on the top of the upper transfer platform, the upper transfer platform being placed on the top of the lower transfer platform, the precision rotating platform moving on the top of the upper transfer platform via a track, the precision rotating platform rotating itself and cooperating with the upper transfer platform to move horizontally to complete a preset spiral path movement, the upper transfer platform moving on the lower transfer platform via a sliding assembly;

[0007] It also includes an initial inspection camera for preliminarily determining the center position and size of the wafer, and an optical inspection module for collecting spectral information by frequency. Both the initial inspection camera and the optical inspection module are located above the precision rotating platform.

[0008] Furthermore, the transfer platform includes a mounting base and a sliding assembly, the sliding assembly includes a slide rail, a slider, a connecting plate, a grating scale, and a reading head. The slide rail is located on the mounting base, the connecting plate is fixed to the top of the slider, and the slider and the connecting plate are moved on the slide rail through a direct drive motor; the grating scale is arranged on the side of the mounting base, and the reading head is kept parallel to the grating scale.

[0009] Furthermore, the precision rotating platform includes an adsorption plate for placing wafers, a torque motor for driving the adsorption plate to rotate is arranged under the adsorption plate, and an adsorption hole is arranged at the center of the adsorption plate.

[0010] A wafer inspection point spiral scanning method is based on the above-mentioned wafer inspection point spiral scanning motion device, and the center coordinates and wafer radius of the wafer to be inspected are obtained according to the wafer image taken by the initial inspection camera. The center of the wafer to be inspected is moved to the center coordinates of the optical inspection module through two transfer platforms. The upper transfer platform cooperates with the rotation angular velocity w of the precision rotating platform at a moving speed v1 to perform equidistant spiral line scanning with a uniform linear speed from the center position of the wafer to be inspected until the edge of the wafer to be inspected is detected, that is, the point spiral scanning inspection of the wafer to be inspected is completed. The specific steps are as follows:

[0011] Step 1. Fix the wafer to be inspected on a precision rotating platform at the initial loading end, use the initial inspection camera to capture the image of the wafer to be inspected, use grayscale and blur processing to pre-process the image to generate image IMG1, use the Canny edge detection method to identify the edge of the wafer to be inspected in image IMG1, and then use the Hough circle transform method to detect the edge of the wafer to be inspected and determine the center of the circle. The radius of the wafer to be inspected is determined by the edge and the center of the circle. The two transfer platforms move in coordination to adjust the center of the wafer to be inspected to just below the center of the optical inspection module. The center of the optical inspection module is the origin of the coordinate system.

[0012] Step 2. The optical detection module collects spectral information of the wafer to be detected at a predetermined frequency. The upper transfer platform moves at a speed v1, and the precision rotating platform rotates at an angular velocity w. The upper transfer platform and the precision rotating platform cooperate to realize the spiral detection trajectory of the wafer. The linear velocity v2 of the scanning spiral is kept constant by continuously changing the speed v1 and the angular velocity w.

[0013] Step 3. When the detection radius of the spiral detection trajectory reaches the radius of the wafer to be detected, the upper transfer platform and the precision rotating platform stop moving, the optical detection module stops collecting spectral information, and the wafer to be detected completes the detection; the two transfer platforms move to the initial loading end in coordination, remove the wafer that has completed the detection, and repeat steps 1 to 3 to complete the detection of all wafers.

[0014] Furthermore, in step 2, the velocity v1, angular velocity w and linear velocity v2 satisfy the following formula:

[0015] v1=bw

[0016]

[0017] Wherein, b is the scanning pitch, and the required pitch width is preset according to the field of view of the high-resolution camera of the optical detection module (10); t is the detection time; and v2 is the linear velocity of the spiral trajectory.

[0018] Furthermore, the velocity v1 and the angular velocity w are determined by the following method:

[0019] r=bθ

[0020] r=v1t

[0021]

[0022] Among them, r is the radius of the current position of the spiral detection trajectory, R is the moving distance of the upper transfer platform, t1 is the time taken from the start of detection to the current detection position, and the rotation axis angle θ=wt.

[0023] Furthermore, the linear velocity v2, velocity v1 and angular velocity w are determined by the following method:

[0024] The coordinates (x, y) of the detection point on the spiral detection trajectory are obtained by x=rcos(θ) and y=rsin(θ):

[0025]

[0026] The linear velocity of the scanning helix And the coordinates of the detection point can be obtained

[0027]

[0028] In summary, the invention has the following beneficial effects:

[0029] The present invention uses a preliminary inspection camera to capture wafer images, combines graying, blurring, Canny edge detection and Hough circle transformation, accurately adjusts the center of the wafer to the center of the optical inspection module, effectively reduces position errors, and improves the accuracy of the inspection results. The present invention uses two transfer platforms to move in a horizontal plane, and cooperates with the rotation of a precision rotating platform to form a spiral trajectory motion, thereby realizing the automated movement of the wafer and point spiral line scanning, reducing manual intervention, and improving inspection efficiency and consistency.

[0030] The spiral scanning path of the present invention can evenly cover the entire wafer surface from the center to the edge of the wafer, ensuring that there is no blind spot in the detection, effectively reducing overlap or omission in the detection process, and improving the reliability and accuracy of the detection; by controlling the translation speed of the upper mobile platform and the angular velocity of the precision rotating platform, the linear speed is kept uniform, which effectively improves the continuity and integrity of the collected spectral data, avoids re-collection and omission of collection points, and can provide high-quality data support for subsequent wafer data analysis.

[0031] The present invention does not need to frequently change the direction of the detection path during the scanning process, nor does it need to frequently start and stop the detection equipment, which reduces the wear and energy consumption of the mechanical system and makes the overall detection process faster and more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the spiral scanning motion device for wafer inspection points of the present invention;

[0033] Figure 2 It is a structural diagram of the mobile platform;

[0034] Figure 3 It is a flow chart of the wafer detection method of the present invention;

[0035] Figure 4 Schematic diagram of spiral scanning trajectory;

[0036] Figure 5 This is a schematic diagram of spiral line equal arc length scanning;

[0037] In the figure, 1 is a mounting base, 2 is a direct drive motor, 3 is a slide rail, 4 is a slider, 5 is a connecting plate, 6 is a grating ruler, 7 is a reading head, 8 is a precision rotating platform, 9 is an initial inspection camera, 10 is an optical inspection module, 11 is a torque motor, 12 is an adsorption plate, and 13 is an adsorption hole. DETAILED DESCRIPTION

[0038] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] like Figures 1 to 5 As shown, the present invention discloses a spiral scanning motion device for wafer inspection points, comprising a precision rotating platform 8 for adsorbing, fixing and rotating wafers, and two transfer platforms for moving wafers. The moving directions of the two transfer platforms are perpendicular to each other, and the wafer can be moved in a radial plane. The precision rotating platform 8 is placed on the top of the upper transfer platform, and the upper transfer platform is placed on the top of the lower transfer platform. The two transfer platforms and the precision rotating platform 8 are respectively the precision rotating platform 8, the upper transfer platform and the lower transfer platform from top to bottom in the vertical direction. The precision rotating platform 8 moves on the top of the upper transfer platform through a track, and the precision rotating platform 8 rotates itself and moves horizontally with the upper transfer platform to complete the preset spiral path movement. The upper transfer platform moves on the lower transfer platform through a sliding component; it also includes an initial inspection camera 9 for preliminarily judging the center position and wafer size of the wafer and an optical detection module 10 for collecting spectral information according to frequency. The initial inspection camera 9 and the optical detection module 10 are both located above the precision rotating platform 8, and the initial inspection camera 9 and the optical detection module 10 are fixed by a bracket structure, and the bracket structure is omitted in the illustrated structure. The optical detection module 10 is a device for collecting spectral information of a wafer.

[0040] The transfer platform includes a mounting base 1 and a sliding assembly, the sliding assembly includes a slide rail 3, a slider 4, a connecting plate 5, a grating scale 6, and a reading head 7. The slide rail 3 is located on the mounting base 1, the connecting plate 5 is fixed to the top of the slider 4, the slider 4 and the connecting plate 5 are moved on the slide rail 3 by a direct drive motor 2, and the direct drive motor 2 is the power source of the transfer platform; the grating scale 6 is arranged on the side of the mounting base 1, the reading head 7 is kept parallel to the grating scale 6, and the reading head 7 is installed on the motor housing.

[0041] The precision rotating platform 8 includes an adsorption plate 12 for placing wafers, a torque motor 11 for driving the adsorption plate 12 to rotate is arranged under the adsorption plate 12, an adsorption hole 13 is arranged at the center position of the adsorption plate 12, and a hollow structure for connecting an air pump pipe is provided on the adsorption plate 12 to realize the pneumatic adsorption function of the wafer.

[0042] The present invention also discloses a wafer detection point spiral scanning method. Based on the above-mentioned wafer detection point spiral scanning motion device, the center coordinates and wafer radius of the wafer to be detected are obtained according to the wafer image taken by the initial inspection camera 9, and the center of the wafer to be detected is moved to the center coordinates of the optical detection module 10 through two transfer platforms. The upper transfer platform cooperates with the rotation angular velocity w of the precision rotating platform 8 at a moving speed v1, and starts to perform equidistant spiral line scanning with a uniform linear speed from the center position of the wafer to be detected. The transfer platform and the precision rotating platform 8 move at the same time to form a spiral line movement trajectory. While moving, the optical detection module 10 performs scanning and detection at a fixed position above the wafer until the edge of the wafer to be detected is detected, that is, the point spiral scanning detection of the wafer to be detected is completed. The specific steps are as follows:

[0043] Step 1. Fix the wafer to be inspected on the precision rotating platform 8 at the initial loading end, use the initial inspection camera 9 to capture the image of the wafer to be inspected, use grayscale and blur processing to pre-process the captured wafer image to generate image IMG1, use the Canny edge detection method to identify the edge of the wafer to be inspected in the image IMG1, and then use the Hough circle transform method to detect the edge of the wafer to be inspected and determine the center of the circle, determine the radius of the wafer to be inspected by the edge and the center of the circle, and the two transfer platforms cooperate to move to adjust the center of the wafer to be inspected to just below the center of the optical inspection module 10. The center of the optical inspection module 10 is the origin of the coordinate system; the center of the wafer is located at the origin of the coordinate system.

[0044] Step 2. The optical detection module 10 collects the spectral information of the wafer to be detected at a predetermined frequency according to the spectral shooting field of view. The predetermined evaluation rate can be adjusted according to the detection requirements. The upper transfer platform moves at a speed v1, and the precision rotating platform 8 rotates at an angular velocity w. The upper transfer platform and the precision rotating platform 8 cooperate to realize the spiral detection trajectory of the wafer. The scanning trajectory is a spiral trajectory through the continuous change of the speed v1 and the angular velocity w, and the linear velocity v2 of the spiral is kept at a constant speed; the speed v1, the angular velocity w and the linear velocity v2 satisfy the following formula:

[0045] v1=bw

[0046]

[0047] Among them, b is the scanning pitch, and the required pitch width is preset according to the high-resolution camera field of view of the optical detection module 10 to ensure the tightness and scanning coverage of the spiral path; t is the detection time; v2 is the linear speed of the spiral trajectory, which is set according to the performance of the detection equipment and the required detection speed.

[0048] The velocity v1 and angular velocity w are determined as follows:

[0049] r=bθ

[0050] r=v1t

[0051]

[0052] Among them, r is the radius of the current position of the spiral detection trajectory, the product of the pitch and the angle is the length, R is the radial distance between the upper transfer platform at the current position and the center of the circle, t1 is the time taken from the start of detection to the current detection position, and the rotation axis angle θ = wt.

[0053] The linear velocity v2, velocity v1 and angular velocity w are determined as follows:

[0054] The coordinates (x, y) of the detection point on the spiral detection trajectory are obtained by x=rcos(θ) and y=rsin(θ):

[0055]

[0056] The linear velocity of the scanning helix And the coordinates of the detection point can be obtained

[0057]

[0058] Step 3. When the detection radius of the spiral detection trajectory reaches the radius of the wafer to be detected, it can be determined that the optical detection module 10 has detected the edge of the wafer, the upper transfer platform and the precision rotating platform 3 stop moving, the optical detection module 10 stops collecting spectral information, and the wafer to be detected is completed; the two transfer platforms move to the initial loading end in coordination, remove the wafer that has completed the detection, and repeat steps 1 to 3 to complete the detection of all wafers. The detection method of the present invention can realize point spiral scanning detection in the radial plane of the wafer.

[0059] It can be seen from the above formulas that the formulas of velocity v1, linear velocity v2 and angular velocity w in the present invention are differentiable everywhere, indicating that during the detection process, the inertial impact on the wafer to be detected is small, which is beneficial to improving the detection accuracy and efficiency of the wafer.

[0060] like Figure 1 As shown, the moving direction of the upper transfer platform is perpendicular to the moving direction of the lower transfer platform, and the wafer can be moved to any position within the radial plane of the wafer.

[0061] like Figure 4 As shown, by setting the pitch b=0.02mm, the fixed spiral trajectory linear speed v2=1mm / s and the total running time as 10 seconds, the angular velocity w(t) and the radial movement speed v1(t) at t=5 seconds and t=10 seconds are calculated using the formula of the present invention.

[0062] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A wafer inspection point spiral scanning motion device, characterized in that: It comprises a precision rotating platform (8) for adsorbing, fixing and rotating wafers, and two transfer platforms for moving wafers, the movement directions of the two transfer platforms are perpendicular to each other, the precision rotating platform (8) is placed on the top of the upper transfer platform, the upper transfer platform is placed on the top of the lower transfer platform, the precision rotating platform (8) moves on the top of the upper transfer platform via a track, the precision rotating platform (8) rotates itself and moves horizontally in coordination with the upper transfer platform to complete a preset spiral path movement, and the upper transfer platform moves on the lower transfer platform via a sliding component; It also includes a preliminary inspection camera (9) for preliminarily determining the center position and size of a wafer and an optical inspection module (10) for collecting spectrum information according to frequency. Both the preliminary inspection camera (9) and the optical inspection module (10) are located above the precision rotating platform (8).

2. The wafer inspection point spiral scanning motion device according to claim 1, characterized in that: The transfer platform comprises a mounting base (1) and a sliding assembly, wherein the sliding assembly comprises a slide rail (3), a slider (4), a connecting plate (5), a grating ruler (6), and a reading head (7), wherein the slide rail (3) is located on the mounting base (1), the connecting plate (5) is fixed to the top of the slider (4), and the slider (4) and the connecting plate (5) are moved on the slide rail (3) by a direct drive motor (2); the grating ruler (6) is arranged on the side of the mounting base (1), and the reading head (7) is kept parallel to the grating ruler (6).

3. The wafer inspection point spiral scanning motion device according to claim 1, characterized in that: The precision rotating platform (8) comprises an adsorption plate (12) for placing wafers, a torque motor (11) for driving the adsorption plate (12) to rotate is arranged below the adsorption plate (12), and an adsorption hole (13) is arranged at the center of the adsorption plate (12).

4. A wafer inspection point spiral scanning method, based on the wafer inspection point spiral scanning motion device according to any one of claims 1 to 3, characterized in that: The center coordinates and the wafer radius of the wafer to be inspected are obtained based on the wafer image taken by the initial inspection camera (9), and the center of the wafer to be inspected is moved to the center coordinates of the optical inspection module (10) through two transfer platforms. The upper transfer platform cooperates with the rotation angular velocity w of the precision rotating platform (8) at a moving speed v1 to perform equidistant spiral line scanning at a uniform linear speed from the center position of the wafer to be inspected until the edge of the wafer to be inspected is detected, thus completing the point spiral scanning inspection of the wafer to be inspected. The specific steps are as follows: Step 1. Fix the wafer to be inspected on the precision rotating platform (8) at the initial loading end, use the initial inspection camera (9) to capture the image of the wafer to be inspected, use grayscale and blur processing to pre-process the image to generate image IMG1, use the Canny edge detection method to identify the edge of the wafer to be inspected in the image IMG1, and then use the Hough circle transform method to detect the edge of the wafer to be inspected and determine the center of the circle, determine the radius of the wafer to be inspected by the edge and the center of the circle, and move the two transfer platforms in coordination to adjust the center of the wafer to be inspected to just below the center of the optical inspection module (10), and the center of the optical inspection module (10) is the origin of the coordinate system; Step 2. The optical detection module (10) collects spectral information of the wafer to be detected at a predetermined frequency, the upper transfer platform moves at a speed v1, and the precision rotating platform (8) rotates at an angular velocity w. The upper transfer platform and the precision rotating platform (8) cooperate to realize the spiral detection trajectory of the wafer. The linear velocity v2 of the scanning spiral is kept constant by continuously changing the speed v1 and the angular velocity w. Step 3. When the detection radius of the spiral detection trajectory reaches the radius of the wafer to be detected, the upper transfer platform and the precision rotating platform (3) stop moving, the optical detection module (10) stops collecting spectral information, and the wafer to be detected completes the detection; the two transfer platforms move to the initial loading end in coordination, remove the wafer that has completed the detection, and repeat steps 1 to 3 to complete the detection of all wafers.

5. The wafer inspection point spiral scanning method according to claim 4, characterized in that: In step 2, the velocity v1, angular velocity w and linear velocity v2 satisfy the following formula: v1=bw Wherein, b is the scanning pitch, and the required pitch width is preset according to the field of view of the high-resolution camera of the optical detection module (10); t is the detection time; and v2 is the linear velocity of the spiral trajectory.

6. The wafer inspection point spiral scanning method according to claim 5, characterized in that: The velocity v1 and angular velocity w are determined by the following method: r=bθ r=v1t Among them, r is the radius of the current position of the spiral detection trajectory, R is the moving distance of the upper transfer platform, t1 is the time taken from the start of detection to the current detection position, and the rotation axis angle θ=wt.

7. The wafer inspection point spiral scanning method according to claim 5, characterized in that: The linear velocity v2, velocity v1 and angular velocity w are determined by the following method: The coordinates (x, y) of the detection point on the spiral detection trajectory are obtained by x=rcos(θ) and y=rsin(θ): The linear velocity of the scanning helix And the coordinates of the detection point can be obtained

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