Automatic wear compensation system for the lower plate and wafer polishing apparatus with the system

Abstract

An automatic wear compensation system for a lower plate and a wafer polishing apparatus having the system are disclosed. This automatic wear compensation system reduces wafer misloading and errors in wafer loading inspection that occur when the distance between the lower plate and the transport robot gradually increases due to wear of the lower plate during the polishing process. The automatic wear compensation system includes an ultrasonic sensor mounted on the transport robot; a gripper located directly below the ultrasonic sensor and mounted on the lower plate; a controller configured to acquire measured distance information by measuring the distance from the gripper using the ultrasonic sensor, compare the measured distance information with the set reference distance information, and generate an adjustment control signal; and a driver configured to automatically adjust the Z-axis position of the transport robot based on the adjustment control signal sent by the controller.

Description

[0001] This application claims the benefit of Korean Patent Application No. 10-2022-0002208, filed on January 6, 2022, which is incorporated herein by reference in its entirety, as fully set forth herein. Background of the Invention Technical Field

[0003] The present invention relates to an automatic wear compensation system for a lower plate and a wafer polishing apparatus having the automatic wear compensation system, and more specifically, to an automatic wear compensation system for a lower plate that reduces errors in wafer misloading and wafer loading inspection that occur when the distance between the lower plate and a transfer robot configured to load wafers onto and unload wafers from the lower plate gradually increases due to wear of the lower plate during the polishing process, and to a wafer polishing apparatus having the automatic wear compensation system. Background Technology

[0005] Generally speaking, silicon wafers are widely used as materials for manufacturing semiconductor devices, and refer to thin single-crystal silicon wafers formed using polycrystalline silicon as raw material.

[0006] This wafer is manufactured by growing a silicon ingot formed of polycrystalline silicon, followed by slicing the ingot into wafer form, planarizing the wafer to have a uniform thickness, etching to remove or eliminate damage caused by mechanical polishing, polishing to smooth the wafer surface, and cleaning the wafer.

[0007] In these processes, during the polishing process, the wafer is located between an upper plate and a lower plate, a paste is injected between the upper and lower plates where the wafer is inserted, and the wafer is rotated and twirled as the upper and lower plates rotate, thereby being polished by the paste.

[0008] Figure 1 This is a conceptual diagram illustrating the wear state of the lower plate between the transfer robot and the lower plate in a conventional grinding system, with part "A" (shaded area) indicating the worn portion of the lower plate.

[0009] refer to Figure 1 When the transfer robot automatically loads and unloads wafers from the lower plate using a 300mm grinding equipment, the lower plate becomes thinner due to friction between the lower plate and the abrasive during the grinding process, and therefore, the distance between the transfer robot and the lower plate gradually increases.

[0010] Therefore, the Z-axis guidance of the transfer robot for wafer position is distorted, resulting in wafer misloading and distance measurement errors using ultrasonic sensors, which may reduce equipment efficiency and increase loss rate.

[0011] Related technical documents

[0012] Patent documents

[0013] (0001) Korean Patent Registration No. 10-2248009 Summary of the Invention

[0014] Therefore, the present invention relates to an automatic wear compensation system for a lower plate and a wafer polishing apparatus having the automatic wear compensation system, which substantially eliminates one or more problems caused by the limitations and disadvantages of related technologies.

[0015] The purpose of this invention is to provide an automatic wear compensation system for a lower plate and a wafer polishing apparatus having the automatic wear compensation system, which can improve errors that occur during wafer misloading and wafer loading inspection.

[0016] To achieve these and other advantages and according to the purposes of the invention, as embodied and broadly described herein, an automatic wear compensation system for a lower plate is configured to uniformly adjust the distance between the lower plate and a transfer robot configured to load and unload wafers onto and from the lower plate. The automatic wear compensation system includes an ultrasonic sensor disposed on the transfer robot; a gripper located directly below the ultrasonic sensor and mounted on the lower plate; a controller configured to acquire measured distance information by measuring the distance from the gripper using the ultrasonic sensor, compare the measured distance information with the set reference distance information, and generate an adjustment control signal; and a driver configured to automatically adjust the Z-axis position of the transfer robot depending on the adjustment control signal sent by the controller.

[0017] The automatic wear compensation system may further include a clamp transfer unit configured to load the clamp onto the lower plate and unload the clamp from the lower plate.

[0018] The reference distance information could be the distance between the ultrasonic sensor and the clamp mounted on the lower plate, initially measured after the lower plate was replaced.

[0019] The measured distance information may include the reference distance information and the wear thickness of the lower plate, and the Z-axis position of the conveying robot is adjusted to move the wear thickness of the lower plate downward.

[0020] The clamp is installed in a hole formed in a carrier coupled to the lower plate.

[0021] In another aspect of the invention, a wafer polishing apparatus is provided, which has an automatic wear compensation system with the characteristics described above. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate (multiple) embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0023] Figure 1 This is a conceptual diagram illustrating the wear state of the lower plate between the transfer robot and the lower plate in a conventional grinding system;

[0024] Figure 2 This is a block diagram of an automatic wear compensation system for a lower plate according to an embodiment of the present invention; and

[0025] Figure 3 and Figure 4 This is a conceptual diagram showing the usage state of a wafer polishing apparatus with an automatic wear compensation system according to the present invention. Detailed Implementation

[0026] In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0027] In the accompanying drawings, elements are shown enlarged, omitted, or schematically for ease of description and clarity. Furthermore, the dimensions of elements do not indicate their actual size. Where possible, the same reference numerals will be used in all drawings to refer to the same parts.

[0028] Figure 2 This is a block diagram of an automatic wear compensation system for a lower plate according to an embodiment of the present invention. Furthermore, Figure 3 and Figure 4 This is a conceptual diagram showing the use of a wafer polishing apparatus with an automatic wear compensation system according to the invention, and more specifically, Figure 3 This is a view showing the status of acquiring reference distance information or measured distance information between the transfer robot and the gripper using an automatic wear compensation system, and Figure 4 This is a view showing the state of the vertical distance of the delivery robot being adjusted using reference distance information and measured distance information.

[0029] By adopting Figure 2 The automatic wear compensation system shown is used for Figure 3 and Figure 4 The wafer polishing apparatus shown, and therefore, reference Figures 2 to 4 The automatic wear compensation system according to the present invention and the wafer polishing apparatus having the automatic wear compensation system will be described together, and for convenience, detailed descriptions of well-known structures and operating states will be omitted.

[0030] According to the invention, the automatic wear compensation system 10 of the lower plate 22 uniformly adjusts the distance between the transfer robot 11 and the lower plate 22, the transfer robot 11 being configured to load wafers onto and unload wafers from the lower plate 22. Figure 2 As shown, the automatic wear compensation system 10 may include a transfer robot 11, an ultrasonic sensor 12, a fixture 13, a controller 14, and a driver 15, and may further include a fixture transfer unit 16. The wafer polishing apparatus 20 according to the present invention can be understood as an apparatus having the above-described automatic polishing compensation system 10.

[0031] As described above in the background section, when the transfer robot 11 automatically loads and unloads wafers onto and from the lower plate 22 using a 300mm polishing apparatus, the lower plate 22 becomes thinner due to friction between the lower plate 22 and the abrasive during the polishing process, and consequently, the distance between the transfer robot 11 and the lower plate 22 gradually increases. Therefore, the Z-axis guidance of the transfer robot 11 for wafer positioning is distorted, resulting in incorrect wafer loading and distance measurement errors using the ultrasonic sensor 12.

[0032] Therefore, in this invention, the initial reference distance information S1 can be measured using the ultrasonic sensor 12 and the clamp 13. That is, the reference distance information S1 can be obtained by mounting the clamp 13 on the upper surface of the lower plate 22 (e.g., in a hole (not shown) formed in a carrier (not shown) coupled to the lower plate 22) and using the ultrasonic sensor 12 to measure the distance between the transfer robot 11 and the clamp 13. For example, the reference distance information S1 could be the distance information between the ultrasonic sensor 12 and the clamp 13 mounted on the upper surface of the lower plate 22, initially measured after the lower plate 22 has been replaced.

[0033] The ultrasonic sensor 12 and vacuum pad 23 can be connected to one side of the transfer robot 11. The configuration and operating status of the ultrasonic sensor 12, vacuum pad 23 and transfer robot 11 are well known, so their detailed description will be omitted.

[0034] The acquired reference distance information S1 can be stored in the controller 14. For this purpose, a separate memory (not shown) can be provided in the controller 14, and the controller 14 may include a monitor configured to display the corresponding status information. After the reference distance information S1 has been acquired, the clamp 13 mounted on the lower plate 22 is removed, and the well-known grinding process is performed.

[0035] After the grinding process is completed, the wafer is unloaded from the lower plate 22 by the transfer robot 11, and then prepared for the grinding process of the new wafer.

[0036] Here, before the new wafer is polished, the jig is remounted on the lower plate 22, and the distance between the transfer robot 11 and the jig 13 is measured using the ultrasonic sensor 12. This distance is used as distance measurement information S2. The distance measurement information S2 may include reference distance information S1 and the upper wear thickness of the lower plate 22.

[0037] That is, due to the friction between the lower plate 22 and the abrasive during the grinding process, the lower plate 22 becomes thinner, and therefore, the distance between the transfer robot 11 and the lower plate 22 gradually increases. Therefore, the measured distance information S2 can be greater than the reference distance information S1 by the wear thickness of the lower plate 22, and the Z-axis position of the transfer robot 11 is adjusted to reduce the difference between the measured distance information S2 and the reference distance information S1.

[0038] To this end, controller 14 can generate an adjustment control signal C1. The adjustment control signal C1 may include drive control information of driver 15, which depends on the downward adjustment distance of the transfer robot 11. Driver 15 may include a drive servo motor configured to vertically move the transfer robot 11. For example, when the downward adjustment distance of the transfer robot 11 is 0.1 mm, the drive servo motor can be operated to move the transfer robot 11 downward by 0.1 mm.

[0039] The gripper can be mounted on the lower plate 22, positioned directly below the ultrasonic sensor 12. Additionally, a separate gripper transfer unit 16 configured to transfer the gripper 13 can be provided to automatically load and unload the gripper 13 onto and from the upper surface of the lower plate 22. The gripper transfer unit 16 can be constructed using a robotic arm with the same structure as the transfer robot 11, and can be connected to a controller 14 for operation. Alternatively, a worker can manually load and unload the gripper 13 onto and from the upper surface of the lower plate 22.

[0040] The fixture 13 can be unloaded from the lower plate 22 immediately after the reference distance information S1 and the measured distance information S2 are obtained.

[0041] After the transfer robot 11 is adjusted to move downwards, the above-described wafer polishing operation is performed. Once the wafer polishing operation is completed, the above process can be repeated.

[0042] During the repeated processing described above, the conveyor robot 11 is continuously adjusted to move downwards, and when the conveyor robot 11 is adjusted to move downwards by a specified distance or more, the upper plate 21 and the lower plate 22 should be replaced.

[0043] After replacing the upper plate 21 and lower plate 22 with new upper and lower plates, the above process starting from the measurement reference distance information S1 can be repeated.

[0044] As described above, the automatic wear compensation system 10 according to the present invention can improve the errors that occur in wafer misloading and wafer loading inspection as described above, and can move the Z-axis position of the transfer robot 11 downward to reduce the wear thickness of the lower plate 22 to maintain a specified distance between the transfer robot 11 and the lower plate 22, thereby preventing the reduction in efficiency and the increase in wear ratio in the wafer polishing apparatus 20.

[0045] As is evident from the above description, the automatic wear compensation system for the lower plate according to the present invention and the wafer polishing apparatus having the automatic wear compensation system have the following effects.

[0046] First, the automatic wear compensation system can improve the accuracy of wafer misloading and errors that occur during wafer loading inspection.

[0047] Secondly, the automatic wear compensation system can move the Z-axis position of the transfer robot 11 downwards by the wear thickness of the lower plate to maintain a specified distance between the transfer robot and the lower plate, thereby preventing the efficiency reduction and wear ratio increase that are usually caused in the wafer polishing apparatus.

[0048] The features, structures, and effects described in association with the above embodiments are incorporated into at least one embodiment of the present invention, but are not limited to that single embodiment. Furthermore, the features, structures, and effects exemplified in association with the various embodiments can be implemented by those skilled in the art, through combination or modification, in other embodiments. Therefore, anything related to these combinations and modifications should be construed as falling within the scope of the present invention.

Claims

1. An automatic wear compensation system for a lower plate, configured to uniformly adjust the distance between the lower plate and a transfer robot, the transfer robot being configured to load wafers onto and unload wafers from the lower plate, the automatic wear compensation system comprising: An ultrasonic sensor is mounted on the conveying robot. A clamp is located directly below the ultrasonic sensor and is mounted on the lower plate; A controller is configured to acquire measured distance information after the wafer has been ground by measuring the distance from the jig using the ultrasonic sensor, compare the measured distance information with a reference distance from the jig before the wafer has been ground, and generate an adjustment control signal. as well as A driver, configured to automatically adjust the Z-axis position of the conveyor robot based on the adjustment control signal sent by the controller. The measured distance information includes the reference distance information and the wear thickness of the lower plate, and the Z-axis position of the conveying robot is adjusted to move the wear thickness of the lower plate downwards.

2. The automatic wear compensation system of claim 1, further comprising a clamp transfer unit configured to load the clamp onto the lower plate and unload the clamp from the lower plate.

3. The automatic wear compensation system as described in claim 1, characterized in that, The reference distance information is the distance between the ultrasonic sensor and the clamp mounted on the lower plate, initially measured after the lower plate was replaced.

4. The automatic wear compensation system as described in claim 1, characterized in that, The clamp is installed in a hole formed in a carrier coupled to the lower plate.

5. A wafer polishing apparatus, the wafer polishing apparatus having an automatic wear compensation system as described in any one of claims 1-4.

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