Wafer conveying device and control method thereof

Abstract

The embodiments of this specification disclose a wafer transfer device and a control method thereof, a wafer transfer robot, wherein the wafer transfer robot includes multiple control axes and at least two layers of transfer finger modules, at least two layers of the transfer finger modules are movably arranged at the execution ends of the control axes in sequence, and the multiple control axes are used to control the movement of the transfer finger modules; each layer of the transfer finger modules includes at least one wafer transfer blade.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of semiconductor equipment manufacturing technology, and more particularly, to a wafer conveying device and a control method thereof. Background Art

[0002] A wafer refers to a silicon chip used in the manufacture of silicon semiconductor integrated circuits. Since its shape is generally set to be circular, it is called a wafer. A wafer is a substrate used to carry chips in the integrated circuit industry and is generally made of a thin silicon-based material. Various circuit component structures can be processed on the silicon wafer to become an integrated circuit product with specific electrical functions. In the manufacturing process of semiconductor devices, it is often necessary to transfer wafers between different processing machines. For example, EFEM (Equipment Front End Module, front-end transfer module), vacuum transfer structure and other conveying devices are all structures used to transfer wafers in semiconductor processing machines. The conveying structure (such as a semiconductor industrial robot) is the core conveying component of the conveying device such as EFEM, which is used to take and place the wafer to all interfaces and functional units.

[0003] Typically, during the integrated circuit chip production process, silicon wafer substrates are loaded into cassettes (FOUPs), where the substrates are stacked and evenly spaced apart. Typically, for 300mm wafers, each FOUP can hold 25 wafers. Wafers are transferred to and from the FOUPs individually or in groups by the wafer transport system within the semiconductor equipment. Summary of the Invention

[0004] In view of this, embodiments of the present specification provide a wafer transfer device and a control method thereof, which are used to solve the problem of poor wafer transfer efficiency in the prior art.

[0005] The embodiments of this specification adopt the following technical solutions:

[0006] An embodiment of the present specification provides a wafer conveying device, the wafer conveying device comprising:

[0007] A wafer transfer robot, comprising a plurality of control axes and at least two layers of transfer finger modules, wherein the at least two layers of transfer finger modules are movably arranged in sequence at the execution ends of the control axes, and the plurality of control axes are used to control the movement of the transfer finger modules; each layer of the transfer finger modules comprises at least one wafer transfer blade.

[0008] Furthermore, the wafer transfer robot is a five-axis robot.

[0009] Furthermore, the plurality of control axes include:

[0010] A first control axis, a second control axis, and a third control axis for controlling the horizontal transmission and rotation of the transmission finger module;

[0011] A fourth control axis for finger opening and closing control of two wafer transfer blades in the horizontal direction;

[0012] A fifth control axis for controlling the vertical translation of the transmission finger module.

[0013] Furthermore, at least one layer of the transfer finger module includes X wafer transfer blades, wherein X≥3.

[0014] Furthermore, the vertical distance between each of the wafer transfer blades is the same as the stacking distance between adjacent wafers in the wafer box.

[0015] Furthermore, when the wafers in the wafer box are complete, the transfer finger modules on each layer simultaneously extend into the wafer box to grab and transfer the wafers;

[0016] When a wafer is missing in the wafer box, the position of the transfer finger modules on each layer is adjusted according to the position of the missing wafer in the wafer box and the number of the wafer transfer blades, so that the transfer finger modules on a single layer extend into the wafer box to grab and transfer the wafer, thereby avoiding grabbing and transferring the wafer at the missing wafer.

[0017] The present invention also provides a method for controlling a wafer conveying device, the method comprising:

[0018] Control multiple control axes of the wafer transfer robot so that the transfer finger modules on each layer overlap in the vertical direction;

[0019] Extending the transfer finger modules of each layer into the wafer box at the same time, so that each wafer transfer blade in the transfer finger modules of each layer is respectively located under the corresponding wafer in the wafer box;

[0020] Controlling the control axis of the wafer transfer robot and moving the robot arm of the wafer transfer robot upward so that each of the wafer transfer blades holds up the corresponding wafer;

[0021] Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and simultaneously moving the transfer finger modules of each layer out of the wafer box;

[0022] Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and extending the transfer finger modules of each layer into the buffer cavity at the same time;

[0023] Controlling the control axis of the wafer transfer robot and moving the robot arm of the wafer transfer robot downward so that the wafer support plates in the buffer chamber respectively support corresponding wafers;

[0024] The multiple control axes of the wafer transfer robot are controlled to keep the transfer finger modules of each layer overlapping in the vertical direction, and the transfer finger modules of each layer are moved out of the buffer cavity at the same time.

[0025] Furthermore, the plurality of control axes include:

[0026] A first control axis, a second control axis, and a third control axis for controlling the horizontal transmission and rotation of the transmission finger module;

[0027] A fourth control axis for finger opening and closing control of two wafer transfer blades in the horizontal direction;

[0028] A fifth control axis for controlling the vertical translation of the transmission finger module.

[0029] Furthermore, at least one layer of the transfer finger module includes X wafer transfer blades, wherein X≥3.

[0030] At least one of the above technical solutions adopted in the embodiments of this specification can achieve the following beneficial effects:

[0031] By controlling the movement of at least two layers of transfer finger modules through multiple control axes of the wafer transfer robot, at least two layers of transfer finger modules can transfer wafers simultaneously, thereby effectively improving the wafer transfer efficiency.

[0032] In addition, since the number of wafer transfer blades in at least one layer of transfer finger modules is greater than or equal to 3, it can flexibly handle different wafer stacking methods in the wafer box, flexibly handle the random wafer missing situation in the wafer box, and flexibly transition between different wafer boxes and buffer chambers, greatly improving the efficiency and flexibility of wafer transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the embodiments of this specification and constitute a part of the embodiments of this specification. The illustrative embodiments and descriptions of this specification are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0034] Figure 1 A schematic diagram of the specific structure of a wafer conveying device provided in an embodiment of this specification;

[0035] Figure 2 A schematic diagram of a wafer transfer method of a wafer transfer device provided in an embodiment of this specification;

[0036] Figure 3 A schematic diagram of a wafer transfer method for connecting and transitioning multiple wafer cassettes using a wafer transfer device according to an embodiment of this specification;

[0037] Figure 4 A schematic diagram of a wafer conveying method for a wafer conveying device provided in an embodiment of this specification in the case of random wafer shortage in a wafer box;

[0038] Among them, 100, wafer transfer robot, 110, control axis, 111, first control axis, 112, second control axis, 113, third control axis, 114, fourth control axis, 115, fifth control axis, 120, transfer finger module, 121, wafer transfer blade. DETAILED DESCRIPTION

[0039] Generally speaking, the following issues need to be noted during wafer transfer:

[0040] 1) The wafer transfer rate of the wafer transfer robot is crucial to the transfer efficiency of the entire transfer system. For some shorter semiconductor process steps, such as the photoresist ashing and removal process, efficient wafer transfer rates are required, which requires a special design of the robot that conforms to the transfer logic.

[0041] 2) Generally, the design of the robot needs to meet several requirements:

[0042] a) The end effector on the robot can grasp a single wafer or multiple wafers simultaneously; the robot moves and controls the end effector in one, two, or multiple directions;

[0043] b) The robot can flexibly handle different wafer stacking methods in the wafer cassette, such as the situation where there are random wafer shortages in the wafer cassette;

[0044] c) The robot needs to efficiently handle the connection and transition between different wafer boxes.

[0045] However, in the prior art, for equipment with a high wafer output rate, synchronously performing the transfer operation of two wafers may still not meet the output rate requirements of the equipment, and usually a robot arm is required to synchronously perform the transfer operation of multiple wafers.

[0046] Therefore, the embodiments of this specification provide a wafer transfer device and a control method thereof, which controls the movement of at least two layers of transfer finger modules through multiple control axes of the wafer transfer robot, so that at least two layers of transfer finger modules can transfer wafers at the same time, thereby effectively improving the wafer transfer efficiency.

[0047] In addition, since the number of wafer transfer blades in at least one layer of transfer finger modules is greater than or equal to 3, it can flexibly handle different wafer stacking methods in the wafer box, flexibly handle the random wafer missing situation in the wafer box, and flexibly transition between different wafer boxes and buffer chambers, greatly improving the efficiency and flexibility of wafer transfer.

[0048] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the specific embodiments of this specification and the corresponding drawings. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0049] The technical solutions provided by the embodiments of this specification are described in detail below with reference to the accompanying drawings.

[0050] like Figure 1 The figure shows a specific structural diagram of a wafer conveying device provided in an embodiment of this specification.

[0051] The wafer transfer device may include:

[0052] The wafer transfer robot 100 may specifically include multiple control axes 110 and at least two layers of transfer finger modules 120. At least two layers of the transfer finger modules 120 are movably arranged at the execution ends of the control axes 110 in sequence. The multiple control axes 110 are used to control the movement of the transfer finger modules 120. Each layer of the transfer finger modules 120 includes at least one wafer transfer blade 121.

[0053] In the embodiments of this specification, the specific number of the control shafts 110 and the transmission finger modules 120 can be set according to actual usage requirements and is not specifically limited here.

[0054] In addition, the number of wafer transfer blades 121 included in each layer of transfer finger module 120 can also be the same or different, and can be one or more, without specific limitation here, so that it can be flexibly used for different wafer stacking methods in the wafer box, as well as the situation where wafers are missing in the wafer box, effectively improving the wafer transfer efficiency.

[0055] For example, if there are 10 wafers stacked in a wafer box, the wafer transfer robot 100 has a three-layer transfer finger module 120, and the wafer transfer blade 121 of the three-layer transfer finger module 120 is a combination mode of 1, 1 and 3, then only two operations are needed to complete the transfer of 10 wafers in the wafer box.

[0056] In a specific application scenario of the embodiment of this specification, the wafer transfer robot 100 can be a five-axis robot, or other types of robots, which are not specifically limited here.

[0057] Furthermore, the multiple control axes 110 may specifically include:

[0058] A first control axis 111, a second control axis 112 and a third control axis 113 for controlling the horizontal transmission and rotation of the transmission finger module;

[0059] A fourth control axis 114 for finger opening and closing control of two wafer transfer blades 121 in the horizontal direction;

[0060] The fifth control axis 115 is used to control the vertical translation of the transmission finger module 120.

[0061] In the embodiment of this specification, at least one layer of the transfer finger module 120 may specifically include X wafer transfer blades, where X is ≥3.

[0062] In this way, the simultaneous transfer of multiple wafers can be achieved without affecting the transfer efficiency of the wafers, thereby improving the flexibility of the wafer transfer scenario.

[0063] Furthermore, the vertical distance between each of the wafer transfer blades 121 is the same as the stacking distance between adjacent wafers in the wafer box.

[0064] For example, if the stacking distance between adjacent wafers in the wafer box is 10 mm horizontally, then the vertical distance between each wafer transfer blade 121 is also 10 mm. In this way, the wafer transfer blade 121 can be quickly aligned with the position of the corresponding wafer in the wafer box, facilitating the rapid transfer of wafers.

[0065] In the embodiment of this specification, when the wafers in the wafer box are complete, the transfer finger modules of each layer simultaneously extend into the wafer box to grab and transfer the wafers;

[0066] When a wafer is missing in the wafer box, the position of the transfer finger modules on each layer is adjusted according to the position of the missing wafer in the wafer box and the number of the wafer transfer blades, so that the transfer finger modules on a single layer extend into the wafer box to grab and transfer the wafer, thereby avoiding grabbing and transferring the wafer at the missing wafer.

[0067] like Figure 1 As shown, the transfer finger module 120 may include two layers (Pick 1 and Pick 2), wherein Pick 1 includes one wafer transfer blade (Blade 1), and Pick 2 includes X wafer transfer blades, taking X=2 as an example.

[0068] As another application embodiment, Pick 1 may include two wafer transfer blades, and Pick 2 may include one wafer transfer blade, which is not specifically limited here.

[0069] Furthermore, the end effector of the conveying finger may include any one of the two modes of edge holding and vacuum adsorption, which is not specifically limited here.

[0070] A wafer transfer device provided in an embodiment of this specification controls the movement of at least two layers of transfer finger modules through multiple control axes of a wafer transfer robot, so that at least two layers of transfer finger modules can transfer wafers simultaneously, thereby effectively improving the wafer transfer efficiency.

[0071] In addition, since the number of wafer transfer blades in at least one layer of transfer finger modules is greater than or equal to 3, it can flexibly handle different wafer stacking methods in the wafer box, flexibly handle the random wafer missing situation in the wafer box, and flexibly transition between different wafer boxes and buffer chambers, greatly improving the efficiency and flexibility of wafer transfer.

[0072] It should be noted that the above-mentioned specific wafer conveying device is only used as a specific application embodiment and does not limit the scope of the embodiments of this specification. It can also include other specific embodiments, which will not be described one by one here.

[0073] Based on the same inventive idea, Figure 2 A schematic diagram of a wafer transfer method of a wafer transfer device provided in an embodiment of this specification.

[0074] like Figure 2 As shown, the wafer conveying method of the wafer conveying device provided in the embodiment of this specification includes the following steps:

[0075] Step 1: Control the control axes 111 / 112 / 113 / 115 of the wafer transfer robot 100 to keep the upper and lower transfer finger modules 120 vertically overlapped, so that the two transfer finger modules 120 extend into the wafer cassette (FOUP A) at the same time, and the three wafer transfer blades 121 are respectively located below wafer slots 3 / 2 / 1 in the wafer cassette;

[0076] Step 2: Control the control shaft 115 of the wafer transfer robot 100 to move the robot arm of the wafer transfer robot 100 upward so that the three wafer transfer blades 121 respectively hold up the corresponding wafer Slots 3 / 2 / 1;

[0077] Step 3: Control the control axes 111 / 112 / 113 of the wafer transfer robot 100 to keep the upper and lower layers of transfer finger modules 120 overlapping in the vertical direction so that the two layers of transfer finger modules 120 are simultaneously moved out of the wafer box;

[0078] Step 4: Control the control axes 111 / 112 / 113 / 115 of the wafer transfer robot 100 to keep the upper and lower transfer finger modules 120 vertically overlapped so that the two layers of transfer finger modules 120 extend into the buffer cavity (Loadlock A, LLA) at the same time.

[0079] Step 5: Control the control axis 115 of the wafer transfer robot 100 to move the robot arm of the wafer transfer robot 100 downward so that the three wafer support plates in the buffer chamber respectively support the corresponding wafer slots 3 / 2 / 1;

[0080] Step 6: Control the control axes 111 / 112 / 113 of the wafer transfer robot 100 to keep the upper and lower layers of transfer finger modules 120 overlapping in the vertical direction, so that the two layers of transfer finger modules 120 move out of the buffer chamber at the same time to complete a single wafer transfer path.

[0081] In another specific application embodiment of the embodiment of this specification, for the connection and transition between multiple wafer boxes, the specific wafer transmission method and logic are as follows: Figure 3 As shown in Table 1, taking three wafer boxes (FOUP A, FOUP B, FOUP C) and two buffer cavities (LLA, LLB) as an example, each buffer cavity includes three layers of wafer support plates.

[0082] like Figure 3 As shown in Table 1, it is clear that only 25 wafer transfer operations are required to complete the transfer of three full cassettes of wafers. Furthermore, the combination of wafer transfer blades provided in the embodiments of this specification enables flexible transfer between FOUP A and FOUP B, and between FOUP B and FOUP C, significantly improving the efficiency and flexibility of wafer transfer.

[0083] Table 1 Wafer transfer logic table under multi-wafer box situation

[0084]

[0085] In another specific application embodiment of the embodiment of this specification, for processing different wafer stacking methods in a wafer box, such as the situation where there are random wafer shortages in the wafer box, such as Figure 4 As shown in FIG. 1 , when wafer Slot 9 in FOUP A is missing, the wafer is transferred by the following steps:

[0086] Step 1: The lower transfer finger module extends into FOUP A, grabs wafers Slot 7 and 8, and then moves out of the FOUP.

[0087] Step 2: Adjust the vertical position of the wafer transfer robot until the upper transfer finger module reaches the wafer pickup position corresponding to Slot 10;

[0088] Step 3: The upper transfer finger module extends into the wafer box, grabs wafer Slot 10, and then moves out of the wafer box, thereby completing the problem of transferring the missing wafer.

[0089] The above method can also solve the wafer shortage problem in Slot 15 and Slot 16 in the wafer box.

[0090] Furthermore, it should be pointed out that the design of the transmission finger module is not limited to the "1+2" transmission blade design, but can also be in the form of "1+3", "1+4", "1+6", "1+8" and "1+12".

[0091] Based on the same inventive concept, an embodiment of this specification provides a control method for a wafer conveying device, which includes:

[0092] S601: Control multiple control axes of the wafer transfer robot so that the transfer finger modules on each layer overlap in the vertical direction;

[0093] S603: Extending the transfer finger modules of each layer into the wafer box simultaneously, so that each wafer transfer blade in the transfer finger modules of each layer is located under the corresponding wafer in the wafer box;

[0094] S605: Control the control axis of the wafer transfer robot to move the robot arm of the wafer transfer robot upward so that each of the wafer transfer blades holds up the corresponding wafer;

[0095] S607: Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and simultaneously moving the transfer finger modules of each layer out of the wafer box;

[0096] S609: Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and extending the transfer finger modules of each layer into the buffer cavity at the same time;

[0097] S611: Control the control axis of the wafer transfer robot and move the robot arm of the wafer transfer robot downward so that the wafer support plates in the buffer chamber respectively support corresponding wafers;

[0098] S613: Control the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and move the transfer finger modules of each layer out of the buffer cavity at the same time.

[0099] Furthermore, the plurality of control axes may include:

[0100] A first control axis, a second control axis, and a third control axis for controlling the horizontal transmission and rotation of the transmission finger module;

[0101] A fourth control axis for finger opening and closing control of two wafer transfer blades in the horizontal direction;

[0102] A fifth control axis for controlling the vertical translation of the transmission finger module.

[0103] Furthermore, at least one layer of the transfer finger module includes X wafer transfer blades, wherein X≥3.

[0104] An embodiment of this specification provides a control method for a wafer transfer device, which controls the movement of at least two layers of transfer finger modules through multiple control axes of a wafer transfer robot, so that at least two layers of transfer finger modules can transfer wafers simultaneously, thereby effectively improving the wafer transfer efficiency.

[0105] In addition, since the number of wafer transfer blades in at least one layer of transfer finger modules is greater than or equal to 3, it can flexibly handle different wafer stacking methods in the wafer box, flexibly handle the random wafer missing situation in the wafer box, and flexibly transition between different wafer boxes and buffer chambers, greatly improving the efficiency and flexibility of wafer transfer.

[0106] Each embodiment in this specification is described in a progressive manner. Similar parts between the embodiments can be referred to in detail. Each embodiment focuses on the differences from other embodiments. Since it is basically similar to the method embodiment, the description is relatively simple. For relevant parts, refer to the partial description of the method embodiment.

[0107] In the description of the embodiments of this specification, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this specification and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of this specification.

[0108] Unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a communication between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this specification can be understood according to the specific circumstances. In addition, in the description of the embodiments of this specification, unless otherwise specified, "multiple" and "several" mean two or more.

[0109] The above diagrams disclose various embodiments of the present disclosure. For the sake of clarity, many physical details are described in the above description. However, it should be understood that these physical details should not be construed as limiting the present disclosure. In other words, in some embodiments of the present disclosure, these physical details are not essential. Furthermore, to simplify the illustrations, some conventional structures and components are depicted in a simplified schematic manner.

[0110] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the embodiments of this specification.

[0111] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0112] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A wafer transfer method, characterized in that: Transferred by a wafer transfer device, wherein the wafer transfer device comprises: A wafer transfer robot comprising a plurality of control axes and at least two layers of transfer finger modules, wherein the at least two layers of transfer finger modules are sequentially movably arranged at the execution ends of the control axes, and the plurality of control axes are used to control the movement of the transfer finger modules; The plurality of control axes include: A first control axis, a second control axis, and a third control axis for controlling the horizontal transmission and rotation of the transmission finger module; a fourth control axis for controlling the horizontal opening and closing of the two-layer transmission finger modules; and a fifth control axis for controlling the vertical translation of the transmission finger modules; Each layer of the transfer finger modules includes at least one wafer transfer blade; wherein, at least one layer of the transfer finger modules includes 2 or X wafer transfer blades, where X ≥ 3, and another layer of the transfer finger modules includes 1 wafer transfer blade; the layer of the transfer finger modules including the 1 wafer transfer blade is movably connected to the layer of the transfer finger modules including the 2 or X wafer transfer blades via a fourth control axis, so that the layer of the transfer finger modules including the 1 wafer transfer blade can move relative to the layer of the transfer finger modules including the 2 or X wafer transfer blades; When the wafers in the wafer box are complete, the transfer finger modules on each layer simultaneously extend into the wafer box to grab and transfer the wafers; When a wafer is missing in the wafer box, the conveying finger module of a layer including 1 wafer conveying blade is adjusted according to the position of the missing wafer in the wafer box and the number of the wafer conveying blades, and moves relative to the conveying finger module including 2 or X wafer conveying blades, so that the conveying finger module of a layer including 1 wafer conveying blade and the conveying finger module including 2 or X wafer conveying blades are sequentially extended into the wafer box to grab and convey the wafers.

2. The wafer transfer method according to claim 1, wherein: The wafer transfer robot is a five-axis robot.

3. The wafer transfer method according to claim 1, wherein: The vertical distance between each of the wafer transfer blades is the same as the stacking distance between adjacent wafers in the wafer box.

4. A control method for a wafer conveying device, executed based on the wafer conveying method according to any one of claims 1 to 3, characterized in that: When the wafers in the wafer box are complete, the transfer finger modules at each layer simultaneously extend into the wafer box to grab and transfer the wafers. The control method includes: Control multiple control axes of the wafer transfer robot so that the transfer finger modules on each layer overlap in the vertical direction; Extending the transfer finger modules of each layer into the wafer box at the same time, so that each wafer transfer blade in the transfer finger modules of each layer is respectively located under the corresponding wafer in the wafer box; Controlling the control axis of the wafer transfer robot and moving the robot arm of the wafer transfer robot upward so that each of the wafer transfer blades holds up the corresponding wafer; Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and simultaneously moving the transfer finger modules of each layer out of the wafer box; Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and extending the transfer finger modules of each layer into the buffer cavity at the same time; Controlling the control axis of the wafer transfer robot and moving the robot arm of the wafer transfer robot downward so that the wafer support plates in the buffer chamber respectively support corresponding wafers; Controlling the multiple control axes of the wafer transfer robot to keep the transfer finger modules of each layer overlapping in the vertical direction, and simultaneously moving the transfer finger modules of each layer out of the buffer cavity; When a wafer is missing in the wafer box, the position of the transfer finger modules on each layer is adjusted according to the position of the missing wafer in the wafer box and the number of the wafer transfer blades; At least one layer of the transfer finger module includes 2 or X wafer transfer blades, wherein X≥3; and another layer of the transfer finger module includes 1 wafer transfer blade.

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