A 3D optical imaging system and method

Abstract

This invention belongs to the field of semiconductor technology and discloses a 3D optical imaging system and method. The system includes an acquisition unit for acquiring image information of a wafer to be diced; a driving unit for controlling the X, Y, and C-axis movement of a dicing machine and adjusting the position and orientation of the wafer on the worktable; a dicing unit for dicing the wafer; a measurement unit for measuring the position of the dicing focus on the wafer; a data processing unit; and a detection unit including a 3D camera for detecting the back side of the diced wafer. This solution uses a 3D camera to detect the back side of the diced wafer to check whether the dicing path on the back side of the wafer is complete, thereby avoiding damage to the dicing tool and causing edge chipping in the next wafer cut. This invention solves the problem that existing wafer position detection devices do not detect defects on the back side of the wafer.

Description

Technical Field

[0001] This solution belongs to the field of semiconductor technology, specifically involving a 3D optical imaging system and method. Background Technology

[0002] 3D optical imaging is a technology that uses optical principles to acquire three-dimensional information about objects. Through specific optical equipment and algorithms, it can capture and reconstruct the three-dimensional shape and depth information of objects, thereby achieving accurate perception and presentation of the three-dimensional structure of objects.

[0003] During wafer dicing, the wafer needs to be aligned. The current alignment method uses image processing algorithms such as preprocessing, edge extraction, and template matching of the wafer image through a machine vision system to calculate the tilt angle between the wafer dicing track and the machine tool's motion axis, and controls the machine tool's rotation axis to make corresponding rotational adjustments, thereby ensuring that the wafer dicing track is parallel and aligned with the machine tool's motion axis, thus improving the accuracy and efficiency of wafer dicing.

[0004] The step of capturing images of the wafer is crucial because it ensures precise parallel alignment between the wafer dicing ridge and the machine tool's motion axis, thereby improving the accuracy and efficiency of wafer dicing. By capturing wafer images and using image processing algorithms for preprocessing, edge extraction, and template matching, the wafer's position, orientation, and tilt angle between the dicing ridge and the machine tool's motion axis can be accurately calculated. The machine tool's rotation axis can then be adjusted accordingly based on these calculations to ensure the wafer maintains the preset alignment during dicing, thus avoiding dicing deviations.

[0005] A semiconductor wafer position detection device and method are disclosed in existing publication (announcement) number CN118824901A. The device includes a wafer fixing stage, a vision imaging system, a motion control system, and a software system. The fixing stage is used to fix the wafer to be detected. The vision imaging system is located directly above the wafer fixing stage and is used to acquire a first low-magnification wafer image, a first high-magnification wafer image, and a second high-magnification wafer image. The motion control system includes a motion control platform and a motion control card, used to move the wafer fixing stage, assist the vision imaging system in acquiring the first high-magnification wafer image and the second high-magnification wafer image at a first part and a second part of the wafer, respectively, and to complete the first wafer position alignment and the second wafer position alignment.

[0006] For example, the vision imaging system in the aforementioned wafer inspection device only captures wafer images at different magnifications, but does not use 3D optical imaging technology to inspect the back side of the wafer after dicing to check whether the back side dicing path of the wafer is complete, thereby avoiding damage to the dicing tool and causing chipping of the dicing path in the next wafer dicing, resulting in irregular chip edge contours and damage to the chip. Summary of the Invention

[0007] The purpose of this solution is to provide a 3D optical imaging system to address the problem that existing wafer position detection devices do not detect defects on the back side of the wafer.

[0008] To achieve the above objectives, this solution provides a 3D optical imaging system, comprising: The acquisition unit is used to acquire image information of the wafer to be cut; A drive unit is used to control the X, Y, and C axis movements of the dicing machine and to adjust the position and orientation of the wafer on the worktable. A cutting unit, the cutting unit being used to cut wafers; A measuring unit, which is used to measure the position of the cutting focus of the cutting unit on the wafer; The data processing unit is used to receive and identify the image information and cutting focus of the wafer, then compare the image of the wafer with the wafer template, calculate the wafer orientation and alignment error, control the X, Y and C axis movement of the dicing machine to adjust the position of the wafer, and finally control the cutting unit to cut the wafer along the cutting focus. The detection unit includes a 3D camera used to detect the back side of the diced wafer.

[0009] The principle of this solution is as follows: the acquisition unit, driving unit, cutting unit, and measurement unit in this solution are all existing technologies, and will not be elaborated on here. In this solution, a 3D camera is used to inspect the back side of the wafer after cutting to check whether the cutting path on the back side of the wafer is complete, thereby avoiding damage to the cutting tool and causing edge chipping in the next wafer cutting, resulting in irregular chip edge contours and chip damage.

[0010] The advantages of this solution are: it addresses the problem that existing wafer position detection devices cannot detect defects on the back side of the wafer. By introducing a 3D optical imaging system, it detects the dicing ridges on the back side of the wafer. This improves the wafer dicing quality, avoids subsequent edge chipping caused by tool damage, and thus avoids the risk of uneven chip edge contours and chip damage.

[0011] Furthermore, the cutting unit includes a grinding wheel and a drive module for driving the grinding wheel; the cutting unit also includes a conductive head and a first electrostatic generator, the conductive head being electrically connected to the first electrostatic generator, and the conductive head being disposed on the rotating shaft of the grinding wheel; the cutting unit also includes a support platform for supporting the wafer, the support platform being provided with a dust suction plate, the dust suction plate having an opposite charge to the conductive head.

[0012] The principle and effect of this scheme are as follows: (1) During the cutting process of the existing grinding wheel dicing machine, the grinding wheel tool and the wafer surface generate severe friction and collision, which causes the cutting edge to wear gradually. The debris and heat generated during cutting may also damage the cutting edge and make it dull. As a result, the edge contour of the back side of the wafer is not neat when cutting the wafer, causing chipping of the cutting path on the back side of the wafer, and even damaging the chip. See "Research on Silicon Wafer Composite Dicing Process" (Li Yanling, Gao Aimei, Zhang Yali. Research on Silicon Wafer Composite Dicing Process [J]. Special Equipment for Electronic Industry, 2018 (268): 25-28.). Therefore, it is necessary to inspect the grinding wheel tool for defects. (2) The grinding wheel tool in this scheme uses diamond blades. The cutting process of the grinding wheel is all existing technology, and will not be described in detail here. When cutting the wafer, the first electrostatic generator is used to charge the conductive head with positive charge, so that the tool shaft and the tool are positively charged, and thus the dust generated when the tool cuts the wafer is positively charged. After the wafer is diced, the wafer and adhesive film are removed from the carrier stage. Due to the opposite charge between the dust and the dust collection plate, opposite poles attract each other, thus adsorbing the dust onto the dust collection plate.

[0013] Furthermore, the top of the support platform is provided with a support plate, the support plate has several grooves, the shape of the grooves matches the cut wafer, and the grooves have several through holes; it also includes a driving assembly, the driving assembly is used to clamp the support plate and drive the support plate to reciprocate on the inspection platform.

[0014] The principle and effect of this scheme are as follows: (1) After the wafer is cut, it will be divided into several wafers and placed on the carrier plate in an disordered manner. Therefore, it is necessary to arrange the wafers on a tray to facilitate subsequent processing. In this scheme, after the wafer is cut, the adhesive film is removed, the carrier plate is clamped by the drive component, and then the carrier plate is driven to move back and forth on the inspection stage, which will generate periodic regular vibration. Through vibration, the wafers placed on the carrier plate are subjected to different inertial forces. These inertial forces cause the wafers to move. At the same time, since the grooves opened on the carrier plate have a limiting and guiding effect on the wafers, the wafers will be aligned and embedded in the grooves that match their size and contour, thus arranging the wafers on a tray. (2) At the same time, due to the action of the dust suction plate, the dust is attracted by the dust suction plate, so that the dust falls onto the carrier plate. During the reciprocating motion of the carrier plate, the dust will also be shaken off from the through hole onto the dust suction plate.

[0015] Furthermore, the support platform has a cavity, and the dust collection plate is located inside the cavity.

[0016] The principle and effect of this solution are as follows: This is existing technology, the dust collection plate is set in the cavity, and the dust enters the cavity through the through hole, thereby collecting the dust in the cavity.

[0017] Furthermore, the carrier plate is electrically connected to a second electrostatic generator, and the charge on the carrier plate is opposite to the charge on the conductive head.

[0018] The principle and effect of this solution are as follows: When wafers are cut using a grinding wheel, chipping occurs on the back side of the wafer, resulting in irregular chip edge contours and even damage to the chip, which affects the process application. See "Research on Silicon Wafer Composite Dicing Process" (Li Yanling, Gao Aimei, Zhang Yali. Research on Silicon Wafer Composite Dicing Process [J]. Special Equipment for Electronic Industry, 2018(268): 25-28.). This solution uses a 3D camera to detect whether the back side dicing of the wafer is neat after cutting.

[0019] Furthermore, the detection unit also includes a dust cover, which is located outside the 3D camera and is electrically connected to the first electrostatic generator.

[0020] The principle and effect of this scheme are as follows: (1) When the carrier plate moves to the bottom of the 3D camera, the carrier plate is negatively charged by the second electrostatic generator and the dust cover is positively charged by the first electrostatic generator, thereby forming a high voltage DC electric field between the carrier plate and the dust cover. The back of a normal wafer is rectangular, that is, only four vertices are sharp points. The back of a wafer with irregular cuts is incomplete and has multiple sharp points. Due to their sharp shape, these sharp points become the focus of charge accumulation in the electric field, that is, the tip of the charge. When the charge accumulates to a certain extent, it will generate a sufficient electric field strength, resulting in the tip discharge phenomenon, that is, the charge jumps from the tip to the negatively charged carrier plate. This discharge phenomenon will generate a short period of light and heat. At this time, the 3D camera captures these bright spots and sends the bright spot information to the data processing unit. The data processing unit judges them. If four bright spots appear in a single groove of the wafer, it means that the cut on the back of the wafer is flat. If more or less than four bright spots appear in a single groove of the wafer, it means that the cut on the back of the wafer is not flat. At this time, the data processing unit alarms and the inspection personnel record the inspection. (2) Because the bright spots generated by tip discharge are relatively weak Since a large amount of dust is generated in the cutting chamber during wafer cutting, a dust cover is set to shield the 3D camera. Furthermore, since the charge of the dust cover in this solution is the same as that of the dust, like poles repel each other, making it difficult for dust to adhere to the dust cover.

[0021] Furthermore, the dust cover includes a first dust cover and a second dust cover, which together form a dust cover; the detection unit also includes a cylinder, the piston rod of which is fixedly connected to the second dust cover; the detection unit also includes an air pump, which is mounted on the detection platform and is configured to cooperate with the support platform, and the air outlet of the air pump is connected to the air inlet of the cylinder through a pipe.

[0022] The principle and effect of this solution are as follows: (1) When the drive assembly drives the carrier plate to move on the inspection stage to the bottom of the 3D camera, the carrier plate will hit the air pump. The gas generated by the air pump enters the cylinder, thereby causing the piston rod of the cylinder to retract and drive the second dust cover away from the first dust cover, so that there is no obstruction under the lens of the 3D camera. At this time, the wafer on the carrier plate is inspected, avoiding the dust cover from affecting the 3D camera. (2) Since the bright spot generated by the tip discharge is relatively weak, and the light cover may still stick to dust, when capturing the bright spot, the dust cover is opened so that the 3D camera can capture the bright spot without any obstruction.

[0023] Furthermore, the detection unit also includes a touch switch, a solenoid valve, and a nozzle. The touch switch is located on the detection platform and is configured in conjunction with the second dust cover. The touch switch is electrically connected to the solenoid valve, which is connected to the air outlet of the cylinder. The solenoid valve opens when the touch switch loses its contact. The nozzle is located on the first dust cover and is connected to the solenoid valve via a pipe.

[0024] The principle and effect of this solution are as follows: when the second dust cover moves away from the first dust cover, the touch switch loses the resistance of the second dust cover, thereby controlling the solenoid valve to open, allowing the gas in the cylinder to enter the nozzle from the outlet end, thus forming an "air curtain" between the second dust cover and the first dust cover, that is, below the 3D camera lens, to prevent dust from adhering to the 3D camera lens at this time.

[0025] A 3D optical imaging method, comprising using a 3D optical imaging system as described above, includes the following steps: Step S10: Image acquisition. Use an industrial camera to capture images of the wafer placed on the dicing machine table to obtain images of the wafer. Step S20: Image preprocessing, performing grayscale transformation, filtering, threshold segmentation, and edge extraction on the acquired wafer image; Step S30: Construct a template. Based on the known shape and size of the wafer, construct a wafer template containing the right-angled edge features of the wafer. The template is used for subsequent image comparison and error calculation. Step S40: Calculate wafer orientation. In the wafer image extracted in step S20, use the Hough transform algorithm to detect straight line segments in the wafer image, determine the X and Y coordinates of the current wafer on the worktable and the rotation angle θ, so as to determine the direction and position of the wafer. Step S50: Calculate the alignment error. Compare the wafer image determined in step S40 with the wafer template constructed in step S30. Through comparison and analysis, calculate the magnitude and direction of the alignment error of the wafer in the X and Y directions and the rotation angle θ. Step S60: Wafer alignment and positioning. Based on the wafer orientation and existing alignment error calculated in step S50, the position and orientation of the wafer on the worktable are adjusted by controlling the X, Y, and C axis movements of the dicing machine to make the wafer reach the predetermined position and orientation. Step S70: Verify the position. After the wafer is aligned, use an industrial camera to capture the wafer image again, and compare the newly captured image with the wafer template a second time. If the comparison result shows an error and the error exceeds the preset threshold, make fine adjustments based on the feedback information until the deviation between the actual wafer placement position and the wafer template is less than or equal to the preset threshold. Finally, start the grinding wheel dicing machine to cut the wafer. Step S80: Inspect the wafer. The second electrostatic generator charges the carrier plate with a negative charge, and the first electrostatic generator charges the dust cover with a positive charge, so that the back side of the wafer is in a high-voltage DC electric field. The 3D camera detects bright spots and identifies the back side cutting situation of the wafer.

[0026] Furthermore, in step S60, the conductive head is charged with a positive charge by the first electrostatic generator, so that the cutting tool of the grinding wheel 21 is charged with a positive charge. After the wafer is cut, a new support stage is installed, and then the dust collection plate is charged with a negative charge by the second electrostatic generator to clean the dust in the cutting chamber. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a 3D optical imaging system according to the present invention; Figure 2 This is a schematic diagram of the cutting unit of the present invention; Figure 3 This is a top view of the support platform of the present invention; Figure 4 This is a schematic diagram of the internal structure of the support platform of the present invention; Figure 5 This is a schematic diagram of the detection unit of the present invention.

[0028] The reference numerals in the accompanying drawings include: wafer 1, dicing unit 2, grinding wheel 21, conductive head 22, support stage 23, cavity 231, dust suction plate 24, detection unit 3, 3D camera 31, dust cover 32, first dust cover 321, second dust cover 322, cylinder 33, air pump 34, touch switch 35, nozzle 36, support plate 4, groove 41, through hole 42, drive assembly 5, adhesive film 6. Detailed Implementation

[0029] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Please see Figure 1 A 3D optical imaging system includes an acquisition unit, a driving unit, a dicing unit 2, a measurement unit, a data processing unit, and a detection unit 3. The acquisition unit acquires image information of the wafer 1 to be diced; the driving unit controls the X, Y, and C-axis movements of the dicing machine and adjusts the position and orientation of the wafer 1 on the worktable; the dicing unit 2 dices the wafer 1; the measurement unit measures the position of the dicing focus on the wafer 1; the data processing unit receives and identifies the image information and dicing focus of the wafer 1, compares the image of the wafer 1 with the wafer template, calculates the wafer orientation and alignment error, controls the X, Y, and C-axis movements of the dicing machine to adjust the position of the wafer 1, and finally controls the dicing unit to dice the wafer 1 along the dicing focus; the detection unit includes a 3D camera 31, which detects the back side of the diced wafer 1. The acquisition unit, driving unit, measurement unit, and data processing unit are all existing technologies and will not be described in detail here. The back side of wafer 1 after dicing is inspected by a 3D camera to check whether the dicing path on the back side of wafer 1 is complete. This avoids damage to the dicing tool, which could cause chipping of the dicing path in the next dicing of wafer 1, resulting in an uneven chip edge profile and damage to the chip.

[0030] Please see Figures 2-4The cutting unit 2 includes a grinding wheel 21 and a drive module for driving the grinding wheel 21; the cutting unit 2 also includes a conductive head 22 and a first electrostatic generator, the conductive head 22 being electrically connected to the first electrostatic generator and disposed on the rotating shaft of the grinding wheel 21; the cutting unit 2 also includes a support platform 23 for supporting the wafer 1, the support platform 23 being provided with a dust suction plate 24, the dust suction plate 24 carrying an opposite charge to the conductive head 22, the support platform 23 having a cavity 231, and the dust suction plate 24 being disposed within the cavity 231. The cutting process of the grinding wheel 21 is all prior art and will not be described in detail here. When cutting the wafer 1, the first electrostatic generator is used to charge the conductive head 22 with a positive charge, thereby causing the tool shaft and the tool to carry a positive charge, and thus causing the dust generated when the tool cuts the wafer to carry a positive charge. After wafer 1 is cut, wafer 1 and adhesive film 6 are removed from the carrier stage 23. Due to the opposite charge between the dust and the dust collection plate 24, they attract each other and thus the dust is adsorbed onto the dust collection plate 24.

[0031] The top of the support stage 23 is provided with a support plate 4, which has a number of grooves 41. The shape of the grooves 41 matches the diced wafer 1. The grooves 41 have a number of through holes 42. It also includes a drive assembly 5, which is used to hold the support plate 4 and drive the support plate 4 to reciprocate on the inspection stage. The drive assembly 5 is existing technology and will not be described in detail here.

[0032] Specific working principle: After wafer 1 is diced, it is divided into several wafers 1 and placed randomly on the carrier plate 4. Therefore, wafer 1 needs to be arranged on a tray for subsequent processing. After wafer 1 is diced, the adhesive film 6 is removed, and the carrier plate 4 is clamped by the drive assembly 5. Then, the carrier plate 4 is driven to reciprocate on the inspection stage, generating periodic vibrations. Through vibration, the wafers 1 placed on the carrier plate 4 are subjected to different inertial forces. These inertial forces cause the wafers 1 to move. At the same time, because the grooves 41 on the carrier plate 4 restrict and guide the wafers 1, the wafers 1 will align and embed into the grooves 41 that match their size and contour, thus arranging the wafers 1 on a tray. Simultaneously, due to the action of the dust suction plate 24, dust is attracted by the dust suction plate 24, causing the dust to fall onto the carrier plate 4. During the reciprocating motion of the carrier plate 4, dust is also vibrated and shaken off from the through holes 42 onto the dust suction plate 24.

[0033] Please see Figures 3-5 The carrier plate 4 is electrically connected to a second electrostatic generator, and the charge on the carrier plate 4 is opposite to the charge on the conductive head 22; the detection unit 3 also includes a dust cover 32, which is located outside the 3D camera 31 and is electrically connected to the first electrostatic generator.

[0034] The specific working principle is as follows: When the carrier plate 4 moves below the 3D camera 31, a negative charge is applied to the carrier plate 4 through the second electrostatic generator, while a positive charge is applied to the dust cover 32 by the first electrostatic generator, thereby forming a high-voltage DC electric field between the carrier plate 4 and the dust cover 32. A normal wafer 1 has a rectangular back surface, meaning it has only four sharp points. However, a wafer 1 with irregular dicing has an incomplete back surface, resulting in multiple sharp points. Due to their sharp shape, these points become focal points for charge accumulation in the electric field, i.e., charge tips. When the charge accumulates to a certain level, it generates a sufficient electric field strength, leading to a tip discharge phenomenon, where the charge jumps from the tip to the negatively charged carrier plate 4. This discharge phenomenon produces brief light and heat. At this time, the 3D camera 31 captures these bright spots and sends the information to the data processing unit. The data processing unit judges the information. If four bright spots appear in a single groove 41, it indicates that the dicing path on the back of the wafer 1 is smooth. If more or fewer than four bright spots appear in a single groove 41, it indicates that the dicing path on the back of the wafer 1 is uneven. In this case, the data processing unit will sound an alarm, and the inspection personnel will record the results. Meanwhile, since a large amount of dust is generated in the cutting chamber during wafer 1 cutting, a dust cover 32 is set to shield the 3D camera 31. Since the charge on the dust cover 32 is the same as the charge on the dust, like poles repel each other, making it difficult for dust to adhere to the dust cover 32.

[0035] The dust cover 32 includes a first dust cover 321 and a second dust cover 322, which together form the dust cover 32. The detection unit 3 also includes a cylinder 33, whose piston rod is fixedly connected to the second dust cover 322. The detection unit 3 also includes an air pump 34, which is mounted on the detection platform and is configured to cooperate with the support platform 23. The air outlet of the air pump 34 is connected to the air inlet of the cylinder 33 through a pipe. The detection unit 3 also includes a touch switch 35, a solenoid valve, and a nozzle 36. The touch switch 35 is mounted on the detection platform and is configured to cooperate with the second dust cover 322. The touch switch 35 is electrically connected to the solenoid valve, which is connected to the air outlet of the cylinder 33. When the touch switch 35 loses its contact, the solenoid valve opens. The nozzle 36 is mounted on the first dust cover 321 and is connected to the solenoid valve through a pipe.

[0036] Specific working principle: When the drive assembly 5 drives the carrier plate 4 to move on the inspection stage to below the 3D camera 31, the carrier plate 4 will impact the air pump 34. The gas generated by the air pump 34 enters the cylinder 33, causing the piston rod of the cylinder 33 to retract, driving the second dust cover 322 away from the first dust cover 321, so that there is no obstruction under the lens of the 3D camera 31. At this time, the wafer 1 on the carrier plate 4 is inspected to avoid the dust cover 32 affecting the 3D camera 31. After the second dust cover 322 moves away from the first dust cover 321, the touch switch 35 loses the resistance of the second dust cover 322, thereby controlling the solenoid valve to open, allowing the gas in the cylinder 33 to enter the nozzle 36 from the outlet end, thereby forming an "air curtain" between the second dust cover 322 and the first dust cover 321, that is, under the lens of the 3D camera 31, to prevent dust from adhering to the lens of the 3D camera 31.

[0037] To better realize the above-mentioned 3D optical imaging system, the present invention also provides a 3D optical imaging method, including the application of such a 3D optical imaging system, comprising the following steps: Step S10: Image acquisition. Use an industrial camera to capture images of the wafer placed on the dicing machine table to obtain images of the wafer. Step S20: Image preprocessing, performing grayscale transformation, filtering, threshold segmentation, and edge extraction on the acquired wafer image; Step S30: Construct a template. Based on the known shape and size of the wafer, construct a wafer template that includes the right-angled edge features of the wafer. The template is used for subsequent image comparison and error calculation. Step S40: Calculate wafer orientation. In the wafer image extracted in step S20, the Hough transform algorithm is used to detect straight line segments in the wafer image to determine the X and Y coordinates and rotation angle θ of the current wafer on the worktable, so as to determine the orientation and position of the wafer. Step S50: Calculate the alignment error. Compare the wafer image determined in step S40 with the wafer template constructed in step S30. Through comparison and analysis, calculate the magnitude and direction of the alignment error of the wafer in the X and Y directions and the rotation angle θ. Step S60: Wafer alignment and positioning. Based on the wafer orientation and existing alignment error calculated in step S50, the position and orientation of the wafer on the worktable are adjusted by controlling the X, Y, and C axis movements of the dicing machine to make the wafer reach the predetermined position and orientation. Step S70: Verify the position. After the wafer is aligned, use an industrial camera to capture the wafer image again, and compare the newly captured image with the wafer template a second time. If the comparison result shows an error and the error exceeds the preset threshold, make fine adjustments based on the feedback information until the deviation between the actual wafer placement position and the wafer template is less than or equal to the preset threshold. Finally, start the grinding wheel dicing machine to cut the wafer. Step S80: Inspect the wafer. The second electrostatic generator charges the carrier plate with a negative charge, and the first electrostatic generator charges the dust cover with a positive charge, so that the back side of the wafer is in a high-voltage DC electric field. The 3D camera detects bright spots and identifies the back side cutting situation of the wafer.

[0038] Furthermore, in step S60, the conductive head is charged with a positive charge by the first electrostatic generator, so that the cutting tool of the grinding wheel 21 is charged with a positive charge. After the wafer is cut, a new carrier is installed, and then the dust collection plate is charged with a negative charge by the second electrostatic generator to clean the dust in the cutting chamber.

[0039] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A 3D optical imaging system, characterized in that, include: The acquisition unit is used to acquire image information of the wafer (1) to be cut; A drive unit is used to control the X, Y, and C axis movements of the dicing machine and to adjust the position and orientation of the wafer (1) on the worktable. Cutting unit (2), the cutting unit (2) is used to cut wafer (1); A measuring unit is used to measure the position of the cutting focus of the cutting unit on the wafer (1); The data processing unit is used to receive and identify the image information and cutting focus of the wafer (1), then compare the image of the wafer (1) with the wafer template, calculate the wafer orientation and alignment error, control the X, Y and C axis movement of the dicing machine, adjust the position of the wafer (1), and finally control the cutting unit to cut the wafer (1) along the cutting focus. The detection unit (3) includes a 3D camera (31) for detecting the back side of the diced wafer (1); The cutting unit (2) includes a grinding wheel (21) and a driving module for driving the grinding wheel (21); the cutting unit (2) also includes a conductive head (22) and a first electrostatic generator, the conductive head (22) being electrically connected to the first electrostatic generator, the conductive head (22) being mounted on the rotating shaft of the grinding wheel (21); the cutting unit (2) also includes a support platform (23) for carrying the wafer (1), the support platform (23) being provided with a dust suction plate (24), the dust suction plate (24) being connected to the conductive head (22) by an electric current... The load is opposite; the top of the support platform (23) is provided with a support plate (4), the support plate (4) is provided with a number of grooves (41), the shape of the grooves (41) matches the cut wafer (1), and the grooves (41) are provided with a number of through holes (42); it also includes a driving component (5), the driving component (5) is used to clamp the support plate (4) and drive the support plate (4) to reciprocate on the testing platform; the support platform (23) is provided with a cavity (231), and the dust suction plate (24) is provided in the cavity (231).

2. The 3D optical imaging system of claim 1, wherein: The carrier plate (4) is electrically connected to a second electrostatic generator, and the charge on the carrier plate (4) is opposite to the charge on the conductive head (22).

3. The 3D optical imaging system of claim 2, wherein: The detection unit (3) also includes a dust cover (32), which is located outside the 3D camera (31) and is electrically connected to the first electrostatic generator.

4. The 3D optical imaging system of claim 3, wherein: The dust cover (32) includes a first dust cover (321) and a second dust cover (322), which together form the dust cover (32); the detection unit (3) also includes a cylinder (33), whose piston rod is fixedly connected to the second dust cover (322); the detection unit (3) also includes an air pump (34), which is mounted on the detection platform and is configured to cooperate with the support platform (23). The air outlet of the air pump (34) is connected to the air inlet of the cylinder (33) through a pipe.

5. The 3D optical imaging system of claim 4, wherein: The detection unit (3) also includes a touch switch (35), a solenoid valve and a nozzle (36). The touch switch (35) is located on the detection platform. The touch switch (35) is configured in conjunction with the second dust cover (322). The touch switch (35) is electrically connected to the solenoid valve. The solenoid valve is connected to the air outlet of the cylinder (33). The solenoid valve opens after the touch switch (35) loses its contact. The nozzle (36) is located on the first dust cover (321). The nozzle (36) is connected to the solenoid valve through a pipe.

6. A 3D optical imaging method comprising the use of a 3D optical imaging system according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step S10: Image acquisition. Use an industrial camera to capture images of the wafer placed on the dicing machine table to obtain images of the wafer. Step S20: Image preprocessing, performing grayscale transformation, filtering, threshold segmentation, and edge extraction on the acquired wafer image; Step S30: Construct a template. Based on the known shape and size of the wafer, construct a wafer template containing the right-angled edge features of the wafer. The template is used for subsequent image comparison and error calculation. Step S40: Calculate wafer orientation. In the wafer image extracted in step S20, use the Hough transform algorithm to detect straight line segments in the wafer image, determine the X and Y coordinates of the current wafer on the worktable and the rotation angle θ, so as to determine the direction and position of the wafer. Step S50: Calculate the alignment error. Compare the wafer image determined in step S40 with the wafer template constructed in step S30. Through comparison and analysis, calculate the magnitude and direction of the alignment error of the wafer in the X and Y directions and the rotation angle θ. Step S60: Wafer alignment and positioning. Based on the wafer orientation and existing alignment error calculated in step S50, the position and orientation of the wafer on the worktable are adjusted by controlling the X, Y, and C axis movements of the dicing machine to make the wafer reach the predetermined position and orientation. Step S70: Verify the position. After the wafer is aligned, use an industrial camera to capture the wafer image again and compare the newly captured image with the wafer template a second time. If the comparison result shows an error and the error exceeds the preset threshold, make fine adjustments based on the feedback information until the deviation between the actual wafer placement position and the wafer template is less than or equal to the preset threshold. Finally, start the grinding wheel dicing machine to cut the wafer. Step S80: Inspect the wafer. The second electrostatic generator charges the carrier plate with a negative charge, and the first electrostatic generator charges the dust cover with a positive charge, so that the back side of the wafer is in a high-voltage DC electric field. The 3D camera detects bright spots and identifies the back side cutting situation of the wafer.

7. The 3D optical imaging method of claim 6, wherein: In step S60, the conductive head is charged with a positive charge by the first electrostatic generator, so that the cutting tool of the grinding wheel is charged with a positive charge. After the wafer is cut, a new carrier plate is installed. Then, the dust collection plate is charged with a negative charge by the second electrostatic generator to clean the dust in the cutting chamber.

Images