A semiconductor wafer cassette suspension handling apparatus and positioning method

Abstract

A kind of semiconductor wafer box's suspension type handling equipment and positioning method, semiconductor suspension type handling equipment includes overhead crane, clamping device, image acquisition device and control system.The clamping device includes lifting part and clamping part, one end of lifting part is connected with overhead crane, lifting part can be raised relative to overhead crane, clamping part is connected with the other end of lifting part, for clamping wafer box.Image acquisition device is installed on overhead crane, when wafer box is lowered to close to loading and unloading port, image acquisition device acquires the image including wafer box and loading and unloading port, as first image;When wafer box is further lowered to the position of contact and alignment with loading and unloading port, image acquisition device acquires the image including wafer box and loading / unloading port, as second image.Control system can obtain offset compensation value by comparing the characteristics of first image and second image, and offset compensation value is fed back to overhead crane, when overhead crane is lowered behind this loading and unloading port, it can correct error.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to an automated handling system used in the manufacturing of semiconductor integrated circuits. Background Technology

[0002] In semiconductor manufacturing, wafers need to be transferred between different processes. To avoid contamination or damage to the wafers, they are usually placed in wafer cassettes to carry them and facilitate the transfer.

[0003] Typically, wafer cassettes are transferred between different loading / unloading ports using an overhead hoist transfer (OHT) mechanism. In some embodiments, the overhead hoist transfer includes a crane track, a crane, and a clamping device. The crane moves along the track, and the clamping device is connected to the crane. When the crane moves above a loading / unloading port, the clamping device lowers the wafer cassette it has clamped to the loading / unloading port.

[0004] However, the vibrations generated by overhead cranes suspended from the ceiling during long-term operation in semiconductor factories, or track misalignment due to events such as earthquakes, can prevent wafer cassettes from being correctly placed at the loading / unloading port. This misalignment of the wafer cassettes can affect subsequent manufacturing processes and negatively impact semiconductor yield.

[0005] Therefore, how to effectively improve the alignment accuracy between the wafer cassette and the loading / unloading port to improve the yield of semiconductors is an urgent problem to be solved in the semiconductor manufacturing field. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a suspended handling device and positioning method for semiconductor wafer cassettes, which can effectively improve the alignment accuracy between the wafer cassette and the loading / unloading port during overhead lifting and transport.

[0007] To achieve the above objectives, the present invention provides a suspended transport device for semiconductor wafer cassettes, used to transport wafer cassettes carrying semiconductors to loading and unloading ports. The suspended transport device for semiconductors includes an overhead crane, a gripping device, an image capturing device, and a control system.

[0008] The overhead crane is movably mounted on the crane track and can hover above the loading / unloading port. The clamping device includes a lifting section and a clamping section. One end of the lifting section is connected to the overhead crane and can move up and down relative to the crane. The clamping section is connected to the other end of the lifting section and is used to clamp the wafer cassette. An image capturing device is mounted on the overhead crane. When the wafer cassette is lowered close to the loading / unloading port, the image capturing device captures an image including the wafer cassette and the loading / unloading port, as a first image. When the wafer cassette is further lowered to a position where it contacts and aligns with the loading / unloading port, the image capturing device captures an image including the wafer cassette and the loading / unloading port, as a second image. The control system can obtain an offset compensation value by comparing the characteristics of the first and second images and feeds the offset compensation value back to the overhead crane. Furthermore, before the wafer cassette contacts the loading / unloading port for the next lowering, the system is calibrated according to the offset compensation value.

[0009] According to one embodiment, the center line of the image capturing device is collinear with the center lines of the overhead crane, the clamping part, and the wafer cassette, and the image capturing device is positioned directly above the clamping part.

[0010] According to one embodiment, the top surface of the loading and unloading port is provided with a first positioning part, and the bottom surface of the wafer cassette is provided with a second positioning part. When the first positioning part matches the second positioning part, the wafer cassette is aligned with the loading and unloading port.

[0011] According to one embodiment, the first positioning part is a protrusion, and the second positioning part is a groove.

[0012] According to one embodiment, the offset compensation value includes a first direction compensation value, a second direction compensation value, and an angle compensation value.

[0013] According to one embodiment, the image capturing device can mesh a first image and a second image to form a virtual mesh, and obtain a first direction compensation value, a second direction compensation value, and an angle compensation value by comparing the virtual mesh of the first image with the virtual mesh of the second image.

[0014] In another aspect, the present invention provides a method for positioning semiconductor wafer cassettes using a semiconductor suspension transport device as described above, comprising:

[0015] Step 1: The wafer cassette is gripped by the clamping part, and the wafer cassette is lowered to near the loading and unloading port by the lifting part. The image capturing device captures an image including the wafer cassette and the loading and unloading port as the first image.

[0016] Step 2: The wafer cassette is further lowered to a position where it contacts and aligns with the loading / unloading port using the lifting mechanism. The image capturing device captures an image including the wafer cassette and the loading / unloading port, which is used as a second image.

[0017] Step 3: The control system calculates the offset between the first image and the second image by comparing their features, obtains the offset compensation value, and feeds the offset compensation value back to the overhead crane.

[0018] According to one embodiment, in step 3, the offset compensation value includes a first direction compensation value, a second direction compensation value, and an angle compensation value.

[0019] According to one embodiment, step 3 includes: the image capturing device meshes the first image and the second image to form a virtual mesh, and by comparing the virtual mesh of the first image with the virtual mesh of the second image, a first direction compensation value, a second direction compensation value, and an angle compensation value are obtained.

[0020] According to one embodiment, it further includes:

[0021] Step 4: The control system stores the offset compensation value. When the crane performs the next operation of lowering the wafer cassette at the same loading / unloading port, the control system controls the crane to calibrate the offset based on the stored offset compensation value.

[0022] According to one embodiment, it further includes:

[0023] Step 5: After offset calibration, repeat steps 1 to 3 during the wafer cassette placement process to obtain the offset compensation value, and repeat step 4.

[0024] The advantages of this invention compared to the prior art are as follows: The suspended handling equipment of this invention innovatively applies mechanical vision to the precise positioning of wafer cassettes between the suspended handling equipment and the loading and unloading port of the manufacturing equipment. Based on the offset compensation value obtained by image comparison, the error of the next loading of the overhead crane is corrected, so that the overhead crane can perform offset calibration in advance when performing the next wafer cassette loading action, thereby achieving fast and accurate positioning. Attached Figure Description

[0025] Figure 1 This is a suspended transport device for a semiconductor wafer cassette according to an embodiment of the present disclosure.

[0026] Figure 2 A suspended transport device for a semiconductor wafer cassette, according to an embodiment of the present disclosure, lowers the wafer cassette to a first position, and the position diagram of the base and positioning post of the wafer cassette is shown.

[0027] Figure 3 A suspended transport device for a semiconductor wafer cassette, according to an embodiment of the present disclosure, lowers the wafer cassette to a second position. The position diagram of the wafer cassette and the positioning post is shown, wherein, in the second position, the base of the wafer cassette is aligned with the positioning post.

[0028] Figure 4a To illustrate schematically using a grid Figure 2 and Figure 3 The relationship between the locations shown in the diagram.

[0029] Figure 4b for Figure 4a A magnified view of part A in the middle. Detailed Implementation

[0030] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. In the drawings, the thickness of regions and layers may be exaggerated for clarity. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed descriptions will be omitted.

[0031] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details described, or other methods, components, materials, etc., can be employed. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the main technical concept of the invention.

[0032] In related technologies, the positioning method of wafer cassettes between the loading and unloading ports of suspended handling equipment and manufacturing equipment is as follows:

[0033] The clamping device clamps the wafer cassette and lowers it to hover above the positioning post at the loading / unloading port (without touching it). By manually adjusting each axis of the overhead crane, the wafer cassette base is aligned with the positioning post, and the offset of each axis can be obtained.

[0034] Alternatively, a clamping device can be used to clamp a simulated wafer cassette. The device has a touch screen at the bottom. When the simulated wafer cassette is lowered to the loading / unloading port, the positioning post touches the screen to calculate the offset of each axis.

[0035] Next, the calculated offset is sent to all overhead cranes that have completed horizontal and mechanical error adjustments with the reference calibration platform.

[0036] If operational errors occur after prolonged operation, recalibrate according to the above procedures.

[0037] As known from the aforementioned technologies, when long-term operation results in positioning errors between the overhead crane and the loading / unloading port of the manufacturing equipment for the wafer cassette, causing abnormal loading, repositioning is required. This process presents the following problems:

[0038] 1. The overhead crane and the clamping device are connected by a belt. Since the belt is not rigid, the lowering speed of the wafer box needs to be reduced to avoid shaking. Thus, the positioning work of a single loading and unloading port often takes more than 5 minutes.

[0039] 2. When the positioning post touches the touchscreen at the bottom of the device simulating the wafer cassette, any shaking of the touchscreen will decrease the positioning accuracy. To avoid this, the wafer cassette is often lowered / raised repeatedly to obtain an average value and reduce the error. This positioning process for a single loading / unloading port can take more than 10 minutes.

[0040] This invention provides a suspended transport device for semiconductor wafer cassettes, used to transport wafer cassettes 200 carrying semiconductors to loading / unloading ports 100. For example... Figure 1 As shown, the suspended transport equipment for semiconductor wafer cassettes includes a crane 10, a gripping device 20, an image capturing device 30, and a control system (not shown).

[0041] The overhead crane 10 is movably mounted on the crane track and can be suspended above the loading / unloading port. The clamping device 20 includes a lifting part 21 and a clamping part 22. One end of the lifting part 21 is connected to the overhead crane 10 and can rise and fall relative to the overhead crane 10. The clamping part 22 is connected to the other end of the lifting part 21 and is used to clamp the wafer cassette 200. An image capturing device 30 is mounted on the overhead crane 10. When the wafer cassette 200 is lowered close to the loading / unloading port 100, the image capturing device 30 captures an image including the wafer cassette 200 and the loading / unloading port 100, as the first image F1. Figure 2 As shown; when the wafer cassette 200 is further lowered to a position where it contacts and aligns with the loading / unloading port 100, the image capturing device 30 captures an image including the wafer cassette 200 and the loading / unloading port 100, as the second image F2, as shown. Figure 3 As shown. The control system can obtain the offset compensation value by comparing the characteristics of the first image F1 and the second image F2, such as... Figure 4a , 4b As shown, the offset compensation value is fed back to the overhead crane 10, and before the wafer cassette is lowered to the loading and unloading port, it is calibrated according to the offset compensation value.

[0042] The present invention also provides a method for positioning a semiconductor wafer cassette 200, comprising:

[0043] Step 1: The wafer cassette 200 is clamped by the clamping part 22. When the wafer cassette 200 is lowered to near the loading and unloading port 100 by the lifting part 21, the image capturing device 30 captures an image including the wafer cassette 200 and the loading and unloading port 100 as the first image F1.

[0044] Step 2: The wafer cassette 200 is further lowered by the lifting unit 21 to a position where it contacts and aligns with the loading / unloading port 100. The image capturing device 30 captures an image including the wafer cassette 200 and the loading / unloading port 100, which is used as the second image F2; and

[0045] Step 3: The control system calculates the offset between the first image F1 and the second image F2 by comparing their features, obtains the offset compensation value, and feeds back the offset compensation value to the overhead crane 10.

[0046] It may also include:

[0047] Step 4: The control system stores the offset compensation value. When the overhead crane 10 performs the next lowering of the wafer cassette 200 at the same loading / unloading port 100, the control system controls the overhead crane 10 to perform offset calibration according to the stored offset compensation value.

[0048] This may also include:

[0049] Step 5: After offset calibration, repeat steps 1 to 3 during the wafer cassette placement process to obtain the offset compensation value, and repeat step 4.

[0050] In other words, the suspended handling equipment of this invention innovatively applies machine vision to the precise positioning of the wafer cassette 200 between the suspended handling equipment and the loading / unloading port 100 of the manufacturing equipment. Based on the offset compensation value obtained from image comparison, the error of the next wafer cassette placement by the overhead crane 10 is corrected. This allows the overhead crane 10 to pre-calibrate the offset before performing the next wafer cassette 200 placement operation, thereby achieving fast and accurate positioning. Because the overhead crane 10 calibrates according to the updated offset compensation value, it can obtain very accurate calibration data after only a few calibrations, thus significantly shortening the positioning time.

[0051] Compared to related technologies, which require a significant amount of time to realign the loading / unloading port and wafer cassette each time (each alignment takes approximately 5 to 10 minutes or more), the suspended handling equipment of this invention can directly eliminate the aforementioned alignment time, avoiding the impact of downtime on the production line caused by downtime of process equipment and handling systems.

[0052] Furthermore, since this solution is designed to compensate for positioning errors at individual equipment loading and unloading ports of individual crane systems, and is unrelated to hardware errors between cranes, the original requirement for each crane to undergo leveling and mechanical error adjustments at the benchmark calibration table at fixed intervals (monthly / quarterly) can be extended to six months or even a year.

[0053] In this embodiment, as Figure 1As shown, the center line of the image capturing device 30 is collinear with the center lines of the overhead crane 10, the clamping part 22, and the wafer cassette 200, and the image capturing device 30 is positioned directly above the clamping part 22.

[0054] The loading / unloading port 100 has a first positioning part 110 on its top surface and a second positioning part (not shown) on its bottom surface. When the first positioning part 110 matches the second positioning part, the wafer cassette 200 is aligned with the loading / unloading port 100. In this embodiment, the first positioning part 110 is a protrusion and the second positioning part is a groove. Each protrusion can be correspondingly and matched in each groove to achieve alignment between the wafer cassette 200 and the loading / unloading port 100.

[0055] It should be noted that the forms of the first positioning part 110 and the second positioning part are not limited to these; any structure that can achieve alignment can be applied to the present invention.

[0056] In this embodiment, as Figures 2-4b As shown, the image capturing device 30 can mesh the first image F1 and the second image F2 to form a virtual mesh. By comparing the virtual mesh of the first image F1 with the virtual mesh of the second image F2, an offset compensation value is obtained. The offset compensation value may include a first direction compensation value, a second direction compensation value, and an angle compensation value. The first direction is, for example, the X direction, the second direction is, for example, the Y direction, and the angle is, for example, the offset angle of the same line in the mesh. In this embodiment, the offset angle θ is the offset angle of the first vertical line. That is, in this embodiment, the offset compensation value includes the first direction compensation value ΔX, the second direction compensation value ΔY, and the angle compensation value Δθ.

[0057] In this embodiment, the grid is virtual, and it can be a virtual image on the wafer cassette 200, loading / unloading port 100, or gripping device 20.

[0058] In other embodiments, the mesh may be a solid object, which may be formed on the loading / unloading port 100 or the gripping device 20. The image capturing device 30 captures the feature changes of the mesh before and after alignment to determine the offset compensation value.

[0059] Furthermore, the calculation and control of the offset can be achieved using existing methods, so they will not be elaborated here.

[0060] It should be noted that the image format and offset are only illustrative. In other embodiments, the image may be circular, and the offset compensation value is determined by comparing the offset of the circular coordinates.

[0061] In summary, the suspended handling equipment of this invention innovatively applies mechanical vision to the precise positioning of wafer cassettes between the suspended handling equipment and the loading / unloading port of the manufacturing equipment. Based on the offset compensation value obtained by image comparison, the error of the next loading of the overhead crane is corrected, so that the overhead crane can perform offset calibration in advance when performing the next wafer cassette loading action, thereby achieving fast and accurate positioning.

[0062] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A suspended transport device for semiconductor wafer cassettes, used to transport wafer cassettes carrying semiconductors to a loading / unloading port, the suspended transport device for semiconductors comprising: The overhead crane is movably installed on the overhead crane track and can be suspended above the equipment loading and unloading port; The clamping device includes a lifting part and a clamping part. One end of the lifting part is connected to the overhead crane and the lifting part can move up and down relative to the overhead crane. The clamping part is connected to the other end of the lifting part and is used to clamp the wafer cassette. An image capturing device, installed on an overhead crane, captures an image including the wafer cassette and the loading / unloading port when the wafer cassette is lowered to near the loading / unloading port, as a first image; when the wafer cassette is further lowered to a position where it contacts and aligns with the loading / unloading port, the image capturing device captures an image including the wafer cassette and the loading / unloading port, as a second image; and The control system can obtain an offset compensation value by comparing the features of the first image and the second image, and feed the offset compensation value back to the overhead crane. When the wafer cell is lowered for the next time, the system will first be calibrated based on the offset compensation value.

2. The suspended transport device for semiconductor wafer cassettes as described in claim 1, wherein, The centerline of the image capturing device is collinear with the centerlines of the overhead crane, the clamping part, and the wafer cassette, and the image capturing device is positioned directly above the clamping part.

3. The suspended transport device for semiconductor wafer cassettes as described in claim 2, wherein, The top surface of the loading and unloading port is provided with a first positioning part, and the bottom surface of the wafer box is provided with a second positioning part. When the first positioning part matches the second positioning part, the wafer box is aligned with the loading and unloading port.

4. The suspended transport device for semiconductor wafer cassettes as described in claim 3, wherein, The first positioning part is a protruding post, and the second positioning part is a groove.

5. The suspended transport device for a semiconductor wafer cassette as described in claim 1, wherein, The image capturing device can grid the first image and the second image to form a virtual grid. By comparing the virtual grid of the first image with the virtual grid of the second image, a first direction compensation value, a second direction compensation value, and an angle compensation value are obtained.

6. The suspended transport device for a semiconductor wafer cassette as described in claim 5, wherein, When the overhead crane performs the next wafer cassette placement, it first calibrates according to the offset compensation value, and then continues to obtain the first direction compensation value, the second direction compensation value, and the angle compensation value and feeds them back to the overhead crane.

7. A method for positioning a semiconductor wafer cassette using a suspended transport device as described in any one of claims 1 to 6, comprising: Step 1: The wafer cassette is gripped by the clamping part and lowered by the lifting part. When it approaches the loading and unloading port, the image capturing device captures an image including the wafer cassette and the loading and unloading port as the first image. Step 2: The wafer cassette is further lowered to a position where it contacts and aligns with the loading / unloading port using the lifting mechanism. The image capturing device captures an image including the wafer cassette and the loading / unloading port, which is used as a second image. Step 3: The control system calculates the offset between the first image and the second image by comparing their features, obtains the offset compensation value, and feeds the offset compensation value back to the overhead crane.

8. The wafer cassette positioning method as described in claim 7, wherein, Step 3 includes: the image capturing device meshes the first image and the second image to form a virtual mesh, and by comparing the virtual mesh of the first image with the virtual mesh of the second image, obtains a first direction compensation value, a second direction compensation value, and an angle compensation value.

9. The wafer cassette positioning method as described in claim 7, wherein, Also includes: Step 4: The control system stores the offset compensation value. When the crane lowers the wafer cassette to the same loading / unloading port for the next time, the control system controls the crane to calibrate the offset based on the stored offset compensation value.

10. The wafer cassette positioning method as described in claim 9, wherein, Also includes: Step 5: After offset calibration, repeat steps 1 to 3 during the wafer cassette placement process to obtain the offset compensation value, and repeat step 4.

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