Anti-collision wafer taking method and system capable of identifying wafer warping and storage medium

Abstract

The invention provides an anti-collision wafer taking method and system capable of recognizing wafer warping and a storage medium, and the method comprises the steps: arranging a contour collector on a vertical surface of a wafer of an aligner, collecting the contour point data of the wafer in the process that the wafer is rotated by the aligner, and obtaining the contour point data of the wafer; the center position determining module is used for determining the center position of the wafer, the eccentric distance between the center position and the wafer rotation center and the included angle between the projection position of the contour collector on the wafer surface and the direction of the wafer center and the wafer rotation center; according to the eccentric distance, the direction included angle and the known wafer radius, the theoretical distance from the wafer rotation center to the wafer contour is determined under the ideal condition that the wafer is not warped; according to the theoretical distance and the actual distance from the wafer contour to the wafer rotation center, the height difference between the ideal posture and the actual posture of the wafer is determined so as to judge the warping degree of the wafer, and the wafer taking height of the robot is correspondingly adjusted. Therefore, the manipulator is prevented from interfering with the wafer when taking the wafer.

Description

Technical Field

[0001] The present invention relates to wafer retrieval technology, and in particular to a collision-resistant wafer retrieval method and system, and a storage medium capable of identifying wafer warping. Background Art

[0002] As semiconductor manufacturing enters the era of large-scale 300mm / 450mm wafers, wafer warpage has become a key factor affecting lithography alignment accuracy. According to SEMI standards, the allowable warpage for 300mm wafers must be ≤50μm. However, in actual processes (such as 3D NAND multi-layer stacking), warpage often reaches 100-200μm.

[0003] In the semiconductor manufacturing process, the collaborative operation of wafer aligners and cleanroom robots has a significant impact on production efficiency. To optimize production cycle time and shorten overall run time, process engineers typically set the robot's up (up) and down (down) positions to just meet the minimum safe distance between the wafer and the aligner.

[0004] However, this parameter setting that pursues maximum efficiency may bring potential quality risks. For example, when processing wafers with warping deformation, especially when the lowest point of the warping is used as the first wafer picking position of the robot, due to the insufficient actual gap between the robot end effector and the wafer surface, mechanical interference is very likely to occur during the wafer picking process, which may cause scratches on the wafer surface at the least and cracks and damages on the wafer at the worst. This problem is particularly prominent in the automated transmission process of ultra-thin wafers (thickness <100μm) and large-size wafers (300mm and above). Summary of the Invention

[0005] To this end, the main purpose of the present invention is to provide a collision-proof wafer retrieval method and system, and a storage medium that can identify wafer warping, so as to prevent interference between the robot arm and the wafer when retrieval.

[0006] To achieve the above object, according to one aspect of the present invention, a collision-proof wafer retrieval method capable of identifying wafer warpage is provided, comprising the following steps:

[0007] A profile collector is set on the vertical surface of the aligner wafer. When the aligner rotates the wafer, the wafer profile point data is collected to determine the center position of the wafer and its eccentricity with the wafer rotation center, as well as the angle between the projection position of the profile collector on the wafer surface and the wafer center and the wafer rotation center;

[0008] Based on the eccentricity, direction angle, and known wafer radius, determine the theoretical distance from the wafer rotation center to the wafer outline under ideal conditions with no wafer warpage.

[0009] Based on the theoretical distance and the actual distance from the wafer outline to the wafer rotation center, the height difference between the ideal and actual wafer postures is determined to judge the degree of wafer warping and adjust the robot's wafer picking height accordingly.

[0010] In a possible preferred embodiment, the step of calculating the eccentric distance includes:

[0011] Extract the coordinates of all wafer contour points and calculate the initial coordinates of the wafer center using the least squares method;

[0012] Taking the wafer rotation center as the origin, the eccentric distance between the wafer center and the wafer rotation center is calculated based on the initial coordinates of the wafer center.

[0013] In a possible preferred embodiment, the step of calculating the direction angle includes:

[0014] Calculate the actual distance between each wafer contour point and the wafer rotation center ;

[0015] Calculate direction angle :

[0016]

[0017] in is the eccentric distance, is the known wafer radius.

[0018] In a possible preferred embodiment, the step of calculating the theoretical distance includes:

[0019] Calculate theoretical distance :

[0020]

[0021] in is the eccentric distance, For a known wafer radius, is the direction angle.

[0022] In a possible preferred embodiment, the step of determining the degree of wafer warpage includes:

[0023] Calculate the average value of the height difference ratio between the ideal and actual postures of all wafers at each wafer contour point;

[0024] When it is determined that the average value of the height difference ratio is within the collision threshold range, it is considered that the current wafer warpage degree meets the adjustable range.

[0025] In a possible preferred embodiment, the step of calculating the average value of the height difference ratio includes:

[0026] Eliminate wafer contour points in the Notch / Flat area of ​​the wafer contour point data, and assign adjustment weights to wafer contour points in the Notch / Flat symmetric area;

[0027] Calculate the average value of the height difference ratio between the ideal and actual postures of all wafers at the remaining wafer contour points;

[0028] When it is determined that the average value of the height difference ratio is within the collision threshold range, it is considered that the current wafer warpage degree meets the adjustable range.

[0029] In a possible preferred embodiment, the step of adjusting the robot's film picking height accordingly includes:

[0030] judge:

[0031] like , then adjust the robot's film-picking height to:

[0032]

[0033] in is the robot’s initial film-picking height, The height of the aligner rotation platform relative to the robot, To preset the safe buffer distance for picking and placing the film, is the maximum height difference between the ideal and actual wafer postures.

[0034] In a possible preferred embodiment, the step of adjusting the robot's film picking height accordingly further includes:

[0035] judge:

[0036] like , then adjust the robot's film-picking height to:

[0037] .

[0038] In order to achieve the above-mentioned purpose, corresponding to the above-mentioned method example, according to another aspect of the present invention, a collision-avoiding wafer picking system capable of identifying wafer warping is also provided, which includes: a memory, a processor, and a computer program stored in the memory and runnable on the processor, wherein when the processor executes the computer program, the system implements the steps of any of the collision-avoiding wafer picking methods capable of identifying wafer warping as described above.

[0039] In order to achieve the above-mentioned purpose, corresponding to the above-mentioned method example, according to another aspect of the present invention, a computer-readable storage medium is further provided, wherein the computer-readable storage medium stores a computer program, wherein when the computer program is executed, the steps of the anti-collision wafer picking method that can identify wafer warping as described above are implemented.

[0040] The anti-collision wafer picking method, system and storage medium that can identify wafer warpage provided by the present invention cleverly utilize the wafer contour point data extracted by the wafer aligner and contour collector to calculate the height difference between the ideal and actual postures of the wafer, and based on this, realize dynamic quantitative evaluation of the degree of wafer warpage, so that the robot can automatically adjust the picking height according to the actual deformation of the current wafer, thereby realizing full closed-loop control of detection-decision-execution, so as to complete wafer picking under the premise of ensuring no collision risk, and prevent the robot from interfering with the wafer when picking up the wafer, fundamentally solving the industry problems such as wafer breakage and mechanical collision caused by the inability to accurately identify wafer warpage or incorrect compensation in the semiconductor manufacturing process, and providing key guarantees for the automated handling of ultra-thin / large-size wafers in advanced process technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0042] Figure 1 Schematic diagram of the steps of the anti-collision wafer retrieval method capable of identifying wafer warpage of the present invention;

[0043] Figure 2 Schematic diagram of the overall logic flow of the anti-collision wafer retrieval method capable of identifying wafer warpage of the present invention;

[0044] Figure 3 A schematic diagram illustrating the spatial relationship between the aligner, CCD, and wafer, and the orientation of related calculation parameters in the anti-collision wafer retrieval method capable of identifying wafer warpage of the present invention;

[0045] Figure 4 Schematic diagram of weight distribution of wafer flat area in the anti-collision wafer retrieval method capable of identifying wafer warpage of the present invention;

[0046] Figure 5 This is a schematic structural diagram of the anti-collision wafer retrieval system capable of identifying wafer warpage according to the present invention. DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the specific technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments to help those skilled in the art further understand the present invention. Obviously, the embodiments described in this case are only embodiments of a part of the present invention, rather than all embodiments. It should be pointed out that, for those of ordinary skill in the art, the embodiments in this application and the features in the embodiments can be combined with each other without departing from the concept of the present invention and without conflicting with each other. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work should fall within the disclosure and protection scope of the present invention.

[0048] In addition, the terms "first," "second," "S1," "S2," and the like in the specification, claims, and drawings of the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential sequence. It should be understood that the features used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be implemented in an order other than that described herein. Furthermore, the stages described in each step are not necessarily implemented in the same step. It should be understood that the order of implementation of the contents of each step can be adjusted and interchanged without violating the inventive concept, such that the step embodiments of the present invention described herein can be implemented in an order other than that described herein. Furthermore, the terms "including," "having," and any variations thereof, as used herein, are intended to cover non-exclusive inclusions. Unless otherwise expressly specified or limited, the terms "disposed," "arranged," "installed," "connected," and "connected" should be interpreted broadly, for example, to mean fixed, removable, or integral; mechanical or electrical; direct or indirect through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this case based on specific circumstances and in conjunction with prior art.

[0049] In order to prevent the robot from interfering with the wafer when picking up the wafer, the present invention proposes an anti-collision wafer picking method that can identify wafer warping. The concept realizes dynamic quantitative evaluation of the degree of wafer warping by calculating the height difference between the surface contour position of the wafer and the ideal reference plane. At the same time, through data feedback, the robot can automatically determine whether Z-axis position compensation is needed according to the actual deformation of the current wafer, so as to complete wafer picking without collision risk.

[0050] Specifically, if Figures 1 to 3 As shown, the anti-collision wafer retrieval method capable of identifying wafer warpage provided by the present invention includes the following exemplary steps:

[0051] Step S1: A profile collector is set on the vertical surface of the aligner wafer. When the aligner rotates the wafer, the wafer profile point data is collected to determine the center position of the wafer and its eccentric distance from the wafer rotation center, as well as the angle between the projection position of the profile collector on the wafer surface and the wafer center and the wafer rotation center.

[0052] Specifically, in order to identify the height difference between the actual wafer posture and the ideal flat non-warped posture, this example preferably uses the wafer contour point data as an example to illustrate the implementation process. In order to obtain the wafer contour point data, the contour collector can be a laser radar, a charge coupled device (CCD), etc. For example, in this example, CCD is used as an example. Figure 3 As shown, the CCD is preferably arranged in a direction perpendicular to the wafer rotation plane to ensure that when the wafer aligner drives the wafer to rotate, the edges of the wafer are within its collection range.

[0053] When the wafer rotates one circle, all the contour points around the wafer can be collected 360° according to the preset sampling frequency of the CCD. .

[0054] Furthermore, in order to determine the center position of the wafer and its eccentric distance from the wafer rotation center, the calculation steps of this example include:

[0055] Step S11: Extract the coordinates of all wafer contour points and calculate the initial coordinates of the wafer center by the least square method ( , ).

[0056] The example calculation process is as follows:

[0057] ∑ =X1 (calculate the sum of the x coordinates of all points)

[0058] ∑ =Y1 (calculate the sum of the y coordinates of all points)

[0059] ∑ =X2 (calculate the sum of the squares of the x coordinates of all points)

[0060] ∑ =Y2 (calculate the sum of the squares of the y coordinates of all points)

[0061] ∑ =X3 (calculate the sum of the cube of the x coordinates of all points)

[0062] ∑ =Y3 (calculate the sum of the cubics of the y coordinates of all points)

[0063] ∑ =X1Y1 (calculate the sum of the x*y products of all points)

[0064] ∑ =X1Y2 (calculate the sum of the products of x*y² for all points)

[0065] ∑ =X2Y1 (calculate the sum of the x²*y products of all points)

[0066] N = number of contour points

[0067] C=

[0068] D=

[0069] E=

[0070] G=

[0071] H=

[0072] a=

[0073] b=

[0074] final( , )for: 、 .

[0075] Step S12: Taking the wafer rotation center as the origin, and according to the initial coordinates of the wafer center, calculating the eccentric distance between the wafer center and the wafer rotation center.

[0076] Specifically, with the wafer rotation center as the origin (0, 0), the eccentric distance between the wafer center and the wafer rotation center is:

[0077] = .

[0078] Furthermore, to calculate the direction angle, the calculation steps in this example include:

[0079] Step S13 First calculate the contour points of each wafer Actual distance from the wafer rotation center ;

[0080] Step S14: Based on the known wafer radius , and the eccentric distance calculated in the above step S12 , the direction angle can be calculated :

[0081] .

[0082] Step S2: Determine the theoretical distance from the wafer rotation center to the wafer outline under ideal conditions without wafer warpage based on the eccentricity distance, the direction angle, and the known wafer radius.

[0083] Among them, the theoretical distance from the rotation center to the wafer contour point under ideal non-warping conditions is Should be:

[0084]

[0085] in 、 They are the aforementioned already obtained or known eccentricity distance, known wafer radius, and direction angle parameters.

[0086] Step S3 determines the height difference between the ideal and actual wafer postures based on the theoretical distance and the actual distance from the wafer outline to the wafer rotation center to judge the degree of wafer warping and adjust the robot's wafer picking height accordingly.

[0087] Specifically, the exemplary steps of determining the degree of wafer warpage include:

[0088] Step S31: Calculate the contour points of each wafer All wafers are ideal and reality Height difference of posture :

[0089]

[0090] Based on this, the average value Z of the height difference ratio is further calculated, and the maximum height difference under the wafer posture can also be further obtained. , used for subsequent robot height adjustment judgment of film picking.

[0091] On the other hand, reference Figure 4 As shown, considering that the wafer has a notch / flat edge in the Notch / Flat area, in order to improve the calculation accuracy, in an optional embodiment, the step of calculating the average value of the height difference ratio may further include:

[0092] Step S311: Eliminate the Notch / Flat area in the wafer outline data The wafer outline points (optionally including excluding the 3mm area around the Notch / Flat area wafer outline points) and the Notch / Flat symmetric area The wafer contour points are given adjustment weights.

[0093] Considering that warping is symmetrical in general, the Notch / Flat symmetric area is Double weight is given, but those skilled in the art can also make adjustments according to the specific conditions of the wafer structure, and the present invention is not limited thereto.

[0094] Step S312: Calculate the average value of the height difference ratio between the ideal and actual postures of all wafers at the remaining wafer contour points. :

[0095]

[0096]

[0097] in: is the total number of wafer contour points, A piecewise function that assigns different weights to each region, Collect points for a single wafer profile, is the height difference between the warped wafer and the horizontal wafer at each point. It is the theoretical distance from the rotation center to the wafer contour point under ideal conditions without wafer warpage.

[0098] Step S32: When it is determined that the height difference ratio average value Z is within the collision threshold When the wafer warpage is within the adjustable range, it is considered that the current wafer warpage degree meets the adjustable range.

[0099] Among them, the collision threshold , which can generally be set to 0.05 to 0.2 in industrial scenarios with higher tolerance. , but this example is not limited to this, and those skilled in the art can also set different thresholds according to specific scenarios. In addition, when Z is higher than the threshold If the height of the wafer is too high to be adjusted, the warping is considered severe and the robot cannot be adjusted to ensure non-interference operation. Therefore, the warped wafer can be discarded. Otherwise, the conditions for adjusting the robot's height are met.

[0100] Furthermore, as an example, the step of adjusting the height of the robot for picking up the film includes:

[0101] Step S33: The height of the aligner rotation platform relative to the robot is determined based on the known height of the aligner rotation platform. , preset safe buffer distance for picking and placing chips , and the maximum height difference between the ideal and actual wafer postures , adjust the robot's initial film picking height to the interference-free film picking height.

[0102] For example, judge:

[0103] like , then adjust the robot's film-picking height to:

[0104]

[0105] in Example settings: 300~400 Those skilled in the art can also make adjustments according to actual conditions, and the present invention does not limit this.

[0106] Furthermore, in an optional embodiment, the step of adjusting the height of the robot for picking up the film further includes:

[0107] Step S34

[0108] judge:

[0109] like , then adjust the robot's film-picking height to:

[0110] .

[0111] From the above examples, it can be seen that the anti-collision wafer picking method of the present invention that can identify wafer warping cleverly designs a three-dimensional morphology reconstruction scheme to convert the two-dimensional contour point data of the wafer into a three-dimensional morphology, thereby realizing the evaluation of the degree of wafer warping by calculating the height difference between the current posture of the wafer and the ideal horizontal reference plane of the wafer. This has opened up a new direction for evaluating the degree of wafer warping.

[0112] In addition, to improve measurement accuracy, this solution automatically excludes interference data from Notch / Flat contour points and their surrounding areas, and innovatively introduces a symmetrical area weighted compensation mechanism based on the symmetrical characteristics of wafer warpage to ensure the reliability of the calculation results. This accurately realizes the dynamic quantitative evaluation of the degree of wafer warpage, enabling the robot to automatically adjust the picking height according to the actual deformation of the current wafer, thereby realizing a full closed-loop control of detection-decision-execution, so as to complete wafer picking without collision risk and prevent interference between the robot arm and the wafer when taking the wafer. This fundamentally solves industry problems such as wafer breakage and mechanical collision caused by the inability to accurately identify wafer warpage or incorrect compensation in the semiconductor manufacturing process.

[0113] On the other hand, corresponding to the above method example, refer to Figure 5 As shown, the present invention also provides an anti-collision wafer picking system that can identify wafer warping, which includes: a memory, a processor, and a computer program stored in the memory and run on the processor, wherein when the processor executes the computer program, the system implements the steps of the anti-collision wafer picking method that can identify wafer warping as described in any of the above examples.

[0114] On the other hand, corresponding to the above method examples, the present invention also provides a computer-readable storage medium, which stores a computer program, wherein when the computer program is executed, the steps of the anti-collision wafer picking method that can identify wafer warping as described in any of the above examples are implemented.

[0115] In summary, the anti-collision wafer picking method and system, and storage medium that can identify wafer warping provided by the present invention cleverly utilize the wafer contour point data extracted by the wafer aligner and contour collector to calculate the height difference between the ideal and actual postures of the wafer, and based on this, realize dynamic quantitative evaluation of the degree of wafer warping, so that the robot can automatically adjust the picking height according to the actual deformation of the current wafer, thereby realizing full closed-loop control of detection-decision-execution, so as to complete wafer picking under the premise of ensuring no collision risk, and prevent the robot from interfering with the wafer when picking up the wafer, fundamentally solving the industry problems such as wafer breakage and mechanical collision caused by the inability to accurately identify wafer warping or incorrect compensation in the semiconductor manufacturing process, and providing key guarantees for the automated handling of ultra-thin / large-size wafers in advanced process technology.

[0116] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made based on the contents of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0117] Those skilled in the art will understand that, in addition to implementing the systems, devices, units, and their respective modules provided by the present invention in purely computer-readable program code, it is entirely possible to implement the same programs in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. by logically programming the method steps. Therefore, the systems, devices, and their respective modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0118] In addition, all or part of the steps in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a program. The program is stored in a storage medium and includes a number of instructions for causing a single-chip microcomputer, chip, or processor to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, etc., various media that can store program code.

[0119] In addition, various implementations of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A collision-resistant wafer retrieval method capable of identifying wafer warpage, comprising: A profile collector is set on the vertical surface of the aligner wafer. When the aligner rotates the wafer, the wafer profile point data is collected to determine the center position of the wafer and its eccentricity with the wafer rotation center, as well as the angle between the projection position of the profile collector on the wafer surface and the wafer center and the wafer rotation center; Based on the eccentricity, direction angle, and known wafer radius, determine the theoretical distance from the wafer rotation center to the wafer outline under ideal conditions with no wafer warpage. Based on the theoretical distance and the actual distance from the wafer outline to the wafer rotation center, the height difference between the ideal and actual wafer postures is determined to judge the degree of wafer warping and adjust the robot's wafer picking height accordingly.

2. The anti-collision wafer retrieval method capable of identifying wafer warpage according to claim 1, wherein the step of calculating the eccentric distance comprises: Extract the coordinates of all wafer contour points and calculate the initial coordinates of the wafer center using the least squares method; Taking the wafer rotation center as the origin, the eccentric distance between the wafer center and the wafer rotation center is calculated based on the initial coordinates of the wafer center.

3. The anti-collision wafer retrieval method capable of identifying wafer warpage according to claim 1, wherein the step of calculating the direction angle comprises: Calculate the actual distance between each wafer contour point and the wafer rotation center ; Calculate direction angle : ； in is the eccentric distance, is the known wafer radius.

4. The anti-collision wafer retrieval method capable of identifying wafer warpage according to claim 1, wherein the step of calculating the theoretical distance comprises: Calculate theoretical distance : ； in is the eccentric distance, For a known wafer radius, is the direction angle.

5. The anti-collision wafer retrieval method capable of identifying wafer warpage according to claim 1 , wherein the step of determining the degree of wafer warpage comprises: Calculate the average value of the height difference ratio between the ideal and actual postures of all wafers at each wafer contour point; When it is determined that the average value of the height difference ratio is within the collision threshold range, it is considered that the current wafer warpage degree meets the adjustable range.

6. The anti-collision wafer retrieval method capable of identifying wafer warpage according to claim 1, wherein the step of calculating the average value of the height difference ratio comprises: Eliminate wafer contour points in the Notch / Flat area of ​​the wafer contour point data, and assign adjustment weights to wafer contour points in the Notch / Flat symmetric area; Calculate the average value of the height difference ratio between the ideal and actual postures of all wafers at the remaining wafer contour points; When it is determined that the average value of the height difference ratio is within the collision threshold range, it is considered that the current wafer warpage degree meets the adjustable range.

7. The anti-collision wafer picking method capable of identifying wafer warpage according to claim 1, wherein the step of adjusting the wafer picking height of the robot comprises: judge: like , then adjust the robot's film-picking height to: ； in is the robot’s initial film-picking height, The height of the aligner rotation platform relative to the robot, To preset the safe buffer distance for picking and placing the film, is the maximum height difference between the ideal and actual wafer postures.

8. The anti-collision wafer picking method capable of identifying wafer warpage according to claim 7, wherein the step of adjusting the wafer picking height of the robot further comprises: judge: like , then adjust the robot's film-picking height to: 。 9. A wafer warpage-detecting and anti-collision wafer retrieval system comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the system implements the steps of the anti-collision wafer retrieval method capable of identifying wafer warpage as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a computer program, wherein when the computer program is executed, the steps of the anti-collision wafer retrieval method capable of identifying wafer warpage as claimed in any one of claims 1 to 8 are implemented.

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