Four-station full-automatic silicon wafer chamfering machine

Abstract

The four-station full-automatic silicon wafer chamfering machine is provided with four grinding stations, the chamfering machining efficiency of silicon wafers is greatly improved, the four-station full-automatic silicon wafer chamfering machine is circumferentially arranged, a material taking station and a carrying station of a conventional automatic chamfering machine are replaced with wafer robots, the structure of the four-station full-automatic silicon wafer chamfering machine is more compact, the space utilization rate is high, and the technological process is simpler. According to the four-station grinding station, if a grinding wheel of a certain station needs to be replaced in production, the grinding wheel can be replaced without shutdown. And the primary positioning device and the visual centering device are additionally arranged to control and improve the qualified rate of production. Wherein the initial positioning device can preliminarily position the circle center of a silicon wafer, the scanning device can identify and record batch codes on the silicon wafer, so that the processing batch time can be quickly found when problems are found through subsequent inspection, the accurate centering procedure is set at the grinding device, and the silicon wafer is carried to the grinding table for grinding through the carrying mechanism after the circle center is corrected. Therefore, the grinding and cutting precision is improved, and the grinding and cutting device has high practicability and wide applicability.

Description

TECHNICAL FIELD

[0001] The present application relates to a silicon wafer chamfering machine, in particular to a four-station full-automatic silicon wafer chamfering machine, and belongs to the technical field of silicon wafer chamfering. BACKGROUND

[0002] With the rapid development of electronic products, the demand for semiconductor wafers in the electronic market is increasing, and higher requirements are put forward for the quality, specifications and preparation process of wafers. With the rapid development of new energy vehicles, energy transformation and artificial intelligence, the demand for silicon carbide (SiC) has increased significantly, and the demand for cost reduction of silicon carbide has also been increasing.

[0003] The wafer, also known as a silicon wafer, is processed from a silicon ingot and is widely used in the manufacture of integrated circuits after special processing. The later processing of the wafer generally includes cutting, chamfering, cleaning, drying and other steps. Among them, the edge of the wafer formed by cutting is sharp, and if it is directly ground, it is easy to cause edge collapse, thereby causing the silicon wafer to be scrapped, so the silicon wafer needs to be chamfered before grinding.

[0004] The existing automatic equipment for chamfering of round wafers generally has one transfer mechanism and two stations, which has low efficiency in batch production, especially in silicon carbide chamfering. The melting point of silicon carbide is 2700℃, the relative density is 3.217, and it is difficult to process due to high hardness, which takes a long time.

[0005] Some devices allocate a transfer mechanism for transferring wafers between adjacent mechanisms, resulting in a complex structure of the overall wafer chamfering equipment. When the wafer is placed on the grinding table chuck by transferring the wafer, the coaxiality of the wafer and the chuck and the relative angle of the wafer positioning edge cannot be accurately determined, resulting in unstable and uneven chamfering quality of the processed wafer. Manual compensation adjustment is required to meet the processing requirements. This type of equipment is time-consuming to debug and requires experienced debuggers. SUMMARY

[0006] To solve the problems of the prior art, the present application aims to provide a four-station full-automatic silicon wafer chamfering machine.

[0007] In order to achieve the above-mentioned goal, the present application adopts the following technical solution: A four-station full-automatic silicon wafer chamfering machine, comprising a base, four sets of grinding devices are arranged on the cross orthogonal shaft of the top surface of the base, A pair of lifting tables are arranged in the positive half-axis region of the x-axis and the negative half-axis region of the x-axis, respectively, and are arranged between adjacent grinding devices; A cleaning device and an initial positioning device are arranged in the positive half-axis region of the x-axis and the negative half-axis region of the x-axis, respectively, and are arranged between adjacent grinding devices. A wafer robot is arranged at the orthogonal axis point; The lifting table is used for placing a silicon wafer basket, and the wafer robot is used for taking and placing silicon wafers in the silicon wafer basket between the silicon wafer basket, a visual centering device and a grinding device through a mechanical arm; the grinding device is used for grinding the silicon wafers; The initial positioning device is used for obtaining eccentricity data of the silicon wafers and feeding back to a control device, and the control device adjusts the position of the grinding device according to the feedback eccentricity data to correct the eccentricity of the transferred silicon wafers.

[0008] The initial positioning device includes a support seat, a rotating shaft arranged at the top of the support seat, and a loading platform arranged at the top of the rotating shaft; A high-precision digital micrometer is arranged at the top of the support seat through a detection plate, and the high-precision digital micrometer is used for measuring the eccentricity data of the silicon wafers when the rotating shaft rotates, and the control device adjusts the movement of the grinding loading platform according to the obtained eccentricity data to compensate for the eccentricity; Along the longitudinal direction, a group of optical fiber sensors are arranged on both sides of the rotating shaft, respectively, and the optical fiber sensors are used for initial positioning of the silicon wafers placed on the loading platform.

[0009] Further, the initial positioning device is provided with a code scanning assembly connected to the control device, the code scanning assembly is used for reading the code of the silicon wafers and feeding back to the control device for recording, and the control device records the batch code of the silicon wafers according to the feedback code information.

[0010] Further, the initial positioning device is provided with a thickness measuring assembly connected to the control device, the thickness measuring assembly is used for measuring the thickness of the silicon wafers and feeding back to the control device for recording, and the control device determines the defect state of the silicon wafers according to the thickness information.

[0011] The lifting table includes a cylinder, a pair of racks for placing the silicon wafer basket and a plurality of slide rods vertically arranged on the top surface of the base, The racks are parallel to each other and are fixedly connected by a plurality of support rods; The racks are sleeved on the slide rods through slide holes, and the bottom rack is supported and driven by the cylinder; The cylinder is driven by the control device.

[0012] The grinding device includes a main base and a secondary base, The grinding wheel is arranged on the top surface of the main base and is connected to the shaft of the motor arranged in the main base; The secondary base is provided with an X-axis movement module, the X-axis movement module is provided with a Y-axis movement module, and the Y-axis movement module is provided with a Z-axis movement module; the Z-axis movement module is used for driving the grinding table to move along the Z-axis, and the grinding table is provided with a ceramic disc with negative pressure suction holes; The ceramic disc is used for placing a silicon wafer to be ground, and the negative pressure suction hole is used for adsorbing the silicon wafer.

[0013] Further, the top of the base is further provided with a visual centering device, which is used for detecting the coaxiality of the silicon wafer and the ceramic disc, and the reference angle of the silicon wafer. If the silicon wafer is not coaxial or the angle is offset, the control device drives the wafer robot to correct the position of the silicon wafer through the mechanical arm according to the coaxiality and the reference angle fed back by the visual centering device.

[0014] The mechanical arm of the wafer robot is two groups.

[0015] The present application has the advantages of: The four-station full-automatic silicon wafer chamfering machine has four grinding stations, greatly improves the chamfering processing efficiency of the silicon wafer, especially the silicon carbide wafer with a longer processing time. Compared with the conventional automatic chamfering machine, the present application is arranged in a circle, and the wafer robot replaces the material taking station and the carrying station of the conventional automatic chamfering machine, so that the structure is more compact, the space utilization rate is high, and the process flow is simpler. The four-station grinding station can be replaced without stopping the machine if the grinding wheel of any station needs to be replaced, and the other stations can continue to work.

[0016] The present application also has great improvement in process compared with the conventional chamfering machine, and two inspection stations (preliminary positioning device and visual centering device) are added to control and improve the qualified rate of production. The preliminary positioning device can preliminarily determine the center of the silicon wafer, the scanning device can identify the batch code on the silicon wafer and record it, which is convenient for subsequent inspection to quickly find the processing batch time, combined with the process and equipment debugging at that time to analyze and find the problem, so as to solve the problem of unqualified production. In addition, the present application sets the accurate centering process at the grinding device; and the conventional chamfering machine usually uses a material taking robot to take the silicon wafer to a measuring station, corrects the center, and then carries it to the grinding table for grinding. In the carrying process, the positioning center may deviate, and finally the desired precision cannot be achieved. The present application solves the problem of different centers of the silicon wafer and the ceramic disc of the grinding table, thereby improving the grinding precision.

[0017] Compared with the conventional chamfering machine, the material station of the present application has smaller space and larger placement position, uses a cylinder to lift the material table, uses the space in the height direction, realizes four-station feeding, improves the feeding amount and processing efficiency, and has strong practicability and wide applicability. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural schematic view of the four-station wafer automatic chamfering machine.

[0019] Figure 2 It is a structural schematic view of the lifting material table.

[0020] Figure 3 This is a schematic diagram of the initial positioning device.

[0021] Figure 4 This is a schematic diagram of the grinding device.

[0022] The meanings of the markings in the attached diagram are as follows: 1. Base, 2. Lifting platform, 3. Silicon wafer basket, 4. Wafer robot, 5. Initial positioning device, 6. Vision centering device, 7. Grinding device, 8. Cleaning device. 1. Cylinder; 10. Material rack; 11. Slide rod; 12. Support rod; 13. Limiting plate; 14. Support base; 15. Rotating shaft; 16. Stage; 17. Detection plate; 18. Scanning assembly; 19. Fiber optic sensor; 20. Thickness measuring assembly. 21. Main base; 22. Ceramic disc; 23. 0-axis rotary module; 24. Z-axis moving module; 25. Y-axis moving module; 26. X-axis moving module; 27. Grinding wheel; 28. Motor shaft. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0024] A four-station fully automatic silicon wafer chamfering machine consists of four sets of grinding devices 7 located on the top surface of the base 1, a pair of lifting platforms 2, an initial positioning device 5, a visual centering device 6, and a cleaning device 8.

[0025] The base is preferably cylindrical.

[0026] On the top surface of the base, a set of orthogonal cross axes consisting of the x-axis and y-axis is defined based on the center. Four grinding devices are evenly distributed on the orthogonal cross axes.

[0027] A pair of lifting platforms are respectively placed between two adjacent grinding devices, preferably in the negative half-axis region of the y-axis, and respectively in the positive and negative half-axis regions of the x-axis. An initial positioning device and a cleaning device are placed between two adjacent grinding devices in the positive half-axis region of the y-axis, preferably the cleaning device is placed in the positive half-axis region of the x-axis, and the initial positioning device is placed in the negative half-axis region of the x-axis.

[0028] The wafer robot 4 is positioned at the orthogonal axis point. Preferably, the wafer robot has two sets of robotic arms, each with multiple joints, enabling movement in multiple degrees of freedom. The ends of the robotic arms are equipped with vacuum forks, where air tubes connect to air channels within the forks. A vacuum generator extracts air from the air channels, causing the silicon wafers to adhere to the forks, thus achieving wafer handling. The movement of the wafer robot's robotic arms is driven by a control device.

[0029] The lifting table is composed of a pair of racks 10, a cylinder 9, a slide bar 11 and a support bar 12. The pair of racks are parallel to each other and are fixedly connected by four support bars. Four slide bars are vertically arranged on the top surface of the base and penetrate the slide holes of the racks. The lower rack is supported by the cylinder and slides along the slide bar. The cylinder is connected to the control device and is driven by the control device. The top of the slide bar is provided with a limiting plate 13.

[0030] The racks of the lifting table are used to place the silicon wafer baskets 3, which are containers used to protect, transport and store wafers. One silicon wafer basket can usually hold 25 silicon wafers.

[0031] The initial positioning device takes the support seat as the base, a rotating shaft 15 is arranged on the top of the support seat 14, and a carrier 16 is fixedly arranged on the top of the rotating shaft. The carrier is used to carry the silicon wafer. On both sides of the rotating shaft, a set of longitudinal optical fiber sensors 19 are arranged, which are used to preliminarily position the silicon wafer, that is, when the mechanical arm takes and places the silicon wafer, it is prevented from having too much deviation. A high-precision digital micrometer is arranged on the top of the support seat through a detection plate 17, and is preferably a high-precision digital micrometer of the LS7000 series of Keyence. The silicon wafer placed on the carrier rotates with the carrier, and the high-precision digital micrometer identifies and scans the peripheral parameters of the silicon wafer to fit and determine the specific eccentric coordinates of the silicon wafer, so as to realize accurate positioning.

[0032] The purpose of the preliminary positioning is to prevent the silicon wafer from being too eccentric to exceed the positioning range of the high-precision digital micrometer. The standard of accurate positioning is to be able to fit and calculate the detailed coordinates of the silicon wafer on the rotating carrier.

[0033] The initial positioning device is also provided with a code scanning assembly 18 and a thickness measuring assembly 20 connected to the control device. The code scanning assembly is used to read the code of the silicon wafer and feed back to the control device for recording. The control device records the batch code of the silicon wafer according to the feedback code information. The thickness measuring assembly is used to measure the thickness of the silicon wafer and feed back to the control device for recording. The control device determines the defect state of the silicon wafer according to the thickness information.

[0034] The thickness measurement is to prevent non-conforming products from being mixed into standard products by screening the thickness of the silicon wafer. The thickness measuring assembly is preferably a non-contact thickness measuring probe.

[0035] The grinding device includes a main base 21 and a secondary base. A grinding wheel 27 is arranged on the top surface of the main base and is connected to the shaft 28 of the motor arranged in the main base. An X-axis moving module 26 is arranged on the secondary base. A Y-axis moving module is arranged on the X-axis moving module. A Z-axis moving module 24 is arranged on the Y-axis moving module. The Z-axis moving module is used to drive the grinding table to move along the Z-axis. A ceramic disc 22 with negative pressure suction holes is arranged on the grinding table through a 0-axis rotating module 23. The ceramic disc is used to place the silicon wafer to be ground, and the negative pressure suction holes are used to adsorb the silicon wafer.

[0036] When the control device according to the obtained eccentricity coordinates, by driving X axis, Y axis, Z axis movement module, moving the polishing table and ceramic disc, to compensate for the eccentricity.

[0037] The top of the base is also provided with a visual centering device (Keyence CV-X series camera), which is used to detect the coaxiality of the silicon wafer and the ceramic disc, and the reference angle of the silicon wafer. If the coaxiality or the angle is offset, the control device drives the wafer robot to correct the position of the silicon wafer through the mechanical arm according to the coaxiality and the reference angle fed back by the visual centering device. Specifically, the eccentricity data of the silicon wafer is obtained by comparing the camera scanning profile with the graphic parameters set in the camera. If it is within the allowed range, it is passed. If it is not within the allowed range, it is picked up again by the wafer robot, and then compensated and adjusted.

[0038] The cleaning device is used to clean the polished wafer.

[0039] Process: 1. The lifting table is lifted and lowered by a cylinder. Before grinding, each silicon wafer basket can hold 25 silicon wafers. After grinding, the silicon wafers are placed back into the silicon wafer basket.

[0040] 2. The mechanical arm of the wafer robot rotates to the specified rack position, and the vacuum fork picks up the wafer to the initial positioning device. First, the code scanning component identifies and records the wafer code, and then the mechanical arm places the wafer in front of the non-contact thickness probe to measure the thickness of the wafer. If the thickness does not meet the requirements, the wafer is returned to the silicon wafer basket. If the thickness meets the requirements, the wafer is placed on the stage by the mechanical arm.

[0041] The rotating stage and the silicon wafer are identified and scanned by a high-precision digital micrometer to determine the specific eccentricity coordinates of the silicon wafer, which are fed back to the control device.

[0042] The identified wafer code facilitates data backup and maintenance.

[0043] After completion, one set of arms takes out the silicon wafer, and the other set of arms continues to place the new silicon wafer for identification.

[0044] 3. The control device adjusts the coordinates of the polishing table and the ceramic disc according to the eccentricity coordinates. The wafer robot places the silicon wafer on the ceramic disc and fixes it by suction. At this time, the polishing table rises to pick up the silicon wafer.

[0045] The grinding table moves to the detection position of the visual centering device, the coaxiality of the center of the silicon wafer and the ceramic disc and the reference angle of the silicon wafer (the silicon wafer is circular, and there is a flat edge or a NOTCH for positioning to ensure the processing quality of the silicon wafer) are detected by the camera. If the centers are not concentric or the angle is offset, the compensation data (the position offset and other information obtained by comparison) are transmitted to the control device, and the control device controls the mechanical arm to make position compensation to the table, and the wafer robot will be re-handled, and the grinding table will be re-positioned.

[0046] 4. After the correction centering, the grinding table is positioned to the grinding position, the organ protection cover above the water tank is cleaned back and forth and then closed, and the grinding is started. Since the grinding time is long, the wafer robot at this time can act on other process flow positions.

[0047] 5. After the grinding is completed, the organ cover is opened, the grinding table is positioned to the waiting cleaning position, and the wafer robot takes the wafer. The wafer robot takes the silicon wafer to the cleaning device to clean the silicon wafer.

[0048] 6. Finally, the mechanical arm puts the cleaned silicon wafer back into the silicon wafer basket in the lifting table.

[0049] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above examples do not limit the present application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. A four-station fully automatic silicon wafer chamfering machine, characterized in that, Including the base, four grinding devices are set on a cross-shaped orthogonal axis on the top surface of the base. In the negative half-axis region of the y-axis, a pair of lifting platforms are respectively located in the positive half-axis region and the negative half-axis region of the x-axis, and are set between adjacent grinding devices; The cleaning device and the initial positioning device are located in the positive half-axis region of the y-axis and the negative half-axis region of the x-axis, respectively, and are positioned between adjacent grinding devices. At the orthogonal axis point, there is a wafer robot; The lifting platform is used to place silicon wafer baskets, and the wafer robot is used to pick up and transfer silicon wafers from the silicon wafer baskets, the vision centering device, and the grinding device using a robotic arm; the grinding device is used to grind the silicon wafers. The initial positioning device is used to acquire the eccentricity data of the silicon wafer and feed it back to the control device. The control device adjusts the position of the polishing device according to the feedback eccentricity data to correct the eccentricity of the transferred silicon wafer.

2. The silicon wafer chamfering machine according to claim 1, characterized in that, The initial positioning device includes a support base, a rotating shaft located on the top of the support base, and a platform fixedly mounted on the top of the rotating shaft. A high-precision digital micrometer is mounted on the top of the support base via a detection plate. The high-precision digital micrometer is used to measure the eccentricity data of the silicon wafer as it rotates with the rotation axis. The control device adjusts the movement of the grinding stage according to the acquired eccentricity data to compensate for the eccentricity. Along the longitudinal direction, on both sides of the rotation axis, a set of fiber optic sensors are respectively provided. The fiber optic sensors are used to perform initial positioning of the silicon wafer placed on the stage.

3. The silicon wafer chamfering machine according to claim 2, characterized in that, The initial positioning device is equipped with a barcode scanning component connected to the control device. The barcode scanning component is used to read the code of the silicon wafer and feed it back to the control device for recording. The control device records the batch code of the silicon wafer based on the feedback coding information.

4. The silicon wafer chamfering machine according to claim 2, characterized in that, The initial positioning device is equipped with a thickness measuring component connected to the control device. The thickness measuring component is used to measure the thickness of the silicon wafer and feed it back to the control device for recording. The control device determines the defect status of the silicon wafer based on the thickness information.

5. The silicon wafer chamfering machine according to claim 1, characterized in that, The lifting platform includes a cylinder, a pair of racks for placing silicon wafer baskets, and several sliding rods suspended from the top surface of the base. The material racks are parallel to each other and are fixedly connected by several support rods; The material racks are respectively fitted onto the slide rods through sliding holes, and the bottom material racks are supported and driven by cylinders; The cylinder is driven by a control device.

6. The silicon wafer chamfering machine according to claim 1, characterized in that, The grinding device includes a main base and a secondary base. The grinding wheel is located on the top surface of the main unit base and is linked by the shaft of the motor located inside the main unit base; The sub-base is provided with an X-axis moving module, the X-axis moving module is provided with a Y-axis moving module, and the Y-axis moving module is provided with a Z-axis moving module; the Z-axis moving module is used to drive the grinding table to move along the Z-axis, and the grinding table is provided with a ceramic disc with negative pressure suction holes; The ceramic disc is used to place the silicon wafer to be ground, and the negative pressure suction hole is used to adsorb the silicon wafer.

7. The silicon wafer chamfering machine according to claim 6, characterized in that, The top of the base is also provided with a visual centering device, which is used to detect the coaxiality of the silicon wafer and the ceramic disk, and the reference angle of the silicon wafer. If there is a misalignment or angular deviation, the control device drives the wafer robot to correct the position of the silicon wafer through the robotic arm based on the coaxiality and reference angle feedback from the vision centering device.

8. The silicon wafer chamfering machine according to claim 1, characterized in that, The wafer robot has two sets of robotic arms.

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