Mask transmission system, transmission method and photoetching equipment

Abstract

The invention provides a mask transmission system, a transmission method and photoetching equipment. The mask transmission system comprises an outer plate library unit, an inner plate library unit, a cache table unit, a plate hand taking and placing unit and a plate hand exchanging unit, the outer plate library unit is configured to receive the masks and transmit the masks to a first handover station; the inner plate library unit is configured to store masks; the cache table unit is configured to temporarily store a mask; the plate taking and placing hand unit is configured to take, place and transmit masks among the first handover station, the inner plate library unit and the cache table unit; the plate exchange hand unit comprises a mask grabbing and positioning mechanism, a plate exchange hand R-axis movement unit, a plate exchange hand Z-axis movement unit, a plate exchange hand X-axis movement unit and a plate exchange hand Y-axis movement unit; and the exchange plate hand unit is configured to pick, place and transmit the mask plate between the cache table unit and the mask table. The mask transmission system provided by the invention can solve the problem of mask transmission for a large-view-field high-NA objective lens exposure machine in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly relates to a mask transfer system, a transfer method, and a lithography apparatus. Background Art

[0002] A lithography machine generally includes components such as an exposure system, a workpiece stage system, a mask stage system, a mask transfer system, and a substrate transfer system. The mask transfer system transfers a mask plate with a chip design pattern to the mask stage. At the same time, the substrate transfer system transfers a substrate from a substrate storage unit to the workpiece stage. The exposure system irradiates the light for exposure onto the mask plate on the mask stage and passes through the projection objective of the exposure system to form an image on the upper surface of the substrate on the workpiece stage.

[0003] The mask transfer system mainly realizes functions such as the external interface of the mask plate, the storage of the mask plate, and the transfer of the mask plate. It is crucial for the reliable, stable, high-precision, high-efficiency, and pollution-free transfer of the mask plate, and is one of the key subsystems of the lithography machine.

[0004] An IC substrate is an important material used to connect a chip to a PCB master in integrated circuit packaging. The IC substrate is similar to a PCB in structure and function and is developed from an HDI board. However, the technical threshold of the IC substrate is much higher than that of HDI and ordinary PCB. It has characteristics such as high density, high precision, high performance, and miniaturization, and has higher requirements for many key process technical parameters such as line width / line pitch. With the continuous development of IC substrate technology, the current line width / line pitch (L / S) of high-end IC substrates applied to FC-BGA (flip chip) can no longer meet the application requirements of high-end process mass production in the market. To meet the application requirements of high-end processes in the market, exposure machines require higher resolution, larger exposure fields, and higher overlay accuracy. Exposure machines with large fields and high NA objectives are the future development trend.

[0005] The working distance of an exposure machine with a large field and high NA (numerical aperture) objective is relatively small (the distance between the object plane and the objective). The mask stage needs to adopt a design scheme of "embedded mask plate", that is, the mask plate is embedded in the mask stage. Generally, the mask plate gripping and releasing mechanism of the existing mask transfer system uses the method of "clamping and flat towing" for mask plate transfer. For example, the Chinese patent application with the publication number CN109388031A discloses a mask transfer system, including a mask fork for transferring the mask plate. The mask fork includes a mask fork body and two fork rods symmetrically connected to the mask fork body. The fork rods include a transfer part for supporting the mask plate and a collision prevention part. The mask fork is suitable for taking out or putting in the mask plate in a "clamping and flat towing" manner from a smif (Standard Mechanical Interface) rack, a cassette, or a mask stage transfer suction cup. The method of "clamping and flat towing" cannot be applied to the design scheme of "embedded mask plate" of an exposure machine with a large field and high NA objective. Summary of the Invention

[0006] The object of the present invention is to provide a mask transfer system, a transfer method and a lithography apparatus, which can solve the problem of mask transfer for a large field of view and high NA objective lens exposure machine in the prior art.

[0007] To solve the above technical problems, the present invention provides a mask transfer system, including an outer mask library unit, an inner mask library unit, a buffer table unit, a mask pick-and-place unit and a mask exchange unit; the outer mask library unit is configured to receive a mask and transfer the mask to a first handover station; the inner mask library unit is configured to store the mask; the buffer table unit is configured to temporarily store the mask; the mask pick-and-place unit is configured to pick up, place and transfer the mask between the first handover station, the inner mask library unit and the buffer table unit; the mask exchange unit includes: a mask grasping, placing and positioning mechanism, a mask exchange unit R-axis movement unit, a mask exchange unit Z-axis movement unit, a mask exchange unit X-axis movement unit, a mask exchange unit Y-axis movement unit; the mask exchange unit R-axis movement unit is configured to drive the mask grasping, placing and positioning mechanism to rotate; the mask exchange unit Z-axis movement unit is configured to drive the mask grasping, placing and positioning mechanism to move up and down along the Z-axis; the mask exchange unit X-axis movement unit is configured to drive the mask grasping, placing and positioning mechanism to move along the X-axis; the mask exchange unit Y-axis movement unit is configured to drive the mask grasping, placing and positioning mechanism to move along the Y-axis; the mask exchange unit is configured to pick up, place and transfer the mask between the buffer table unit and the mask table.

[0008] Further, the mask grasping, placing and positioning mechanism is rotatably installed on the mask exchange unit R-axis movement unit, the mask exchange unit R-axis movement unit is movably installed on the mask exchange unit Z-axis movement unit, the mask exchange unit Z-axis movement unit is movably installed on the mask exchange unit X-axis movement unit, and the mask exchange unit X-axis movement unit is movably installed on the mask exchange unit Y-axis movement unit; the mask exchange unit R-axis movement unit is configured to drive the mask grasping, placing and positioning mechanism to rotate; the mask exchange unit Z-axis movement unit is configured to drive the mask exchange unit R-axis movement unit and the mask grasping, placing and positioning mechanism to move up and down along the Z-axis; the mask exchange unit X-axis movement unit is configured to drive the mask exchange unit Z-axis movement unit, the mask exchange unit R-axis movement unit and the mask grasping, placing and positioning mechanism to move along the X-axis; the mask exchange unit Y-axis movement unit is configured to drive the mask exchange unit X-axis movement unit, the mask exchange unit Z-axis movement unit, the mask exchange unit R-axis movement unit and the mask grasping, placing and positioning mechanism to move along the Y-axis.

[0009] Further, the mask transfer system further includes a pre-alignment unit configured to identify the alignment marks of the mask plate and obtain the position deviation generated during the transfer of the mask plate; the mask plate exchange unit is configured to pick up, place, and transfer the mask plate between the buffer table unit, the pre-alignment unit, and the mask table.

[0010] Further, the buffer table unit includes an upper plate buffer table and a lower plate buffer table. The upper plate buffer table is configured to temporarily store the mask plate required for exposure; the lower plate buffer table is configured to temporarily store the mask plate after the exposure is completed.

[0011] Further, the mask plate pick-up and placement unit includes a mask plate pick-up and placement fork, a mask plate pick-up and placement hand R-axis movement unit, a mask plate pick-up and placement hand Z-axis movement unit, a mask plate pick-up and placement hand X-axis movement unit, and a mask plate pick-up and placement hand Y-axis movement unit; the mask plate pick-up and placement hand R-axis movement unit is configured to drive the mask plate pick-up and placement fork to rotate; the mask plate pick-up and placement hand Z-axis movement unit is configured to drive the mask plate pick-up and placement fork to move up and down along the Z-axis; the mask plate pick-up and placement hand X-axis movement unit is configured to drive the mask plate pick-up and placement fork to move along the X-axis; the mask plate pick-up and placement hand Y-axis movement unit is configured to drive the mask plate pick-up and placement fork to move along the Y-axis.

[0012] Further, the mask plate pick-up and placement fork is rotatably mounted on the mask plate pick-up and placement hand R-axis movement unit, the mask plate pick-up and placement hand R-axis movement unit is movably mounted on the mask plate pick-up and placement hand Z-axis movement unit, the mask plate pick-up and placement hand Z-axis movement unit is movably mounted on the mask plate pick-up and placement hand Y-axis movement unit, and the mask plate pick-up and placement hand Y-axis movement unit is movably mounted on the mask plate pick-up and placement hand X-axis movement unit; the mask plate pick-up and placement hand R-axis movement unit is configured to drive the mask plate pick-up and placement fork to rotate; the mask plate pick-up and placement hand Z-axis movement unit is configured to drive the mask plate pick-up and placement hand R-axis movement unit and the mask plate pick-up and placement fork to move up and down along the Z-axis; the mask plate pick-up and placement hand Y-axis movement unit is configured to drive the mask plate pick-up and placement hand Z-axis movement unit, the mask plate pick-up and placement hand R-axis movement unit, and the mask plate pick-up and placement fork to move along the Y-axis; the mask plate pick-up and placement hand X-axis movement unit is configured to drive the mask plate pick-up and placement hand Y-axis movement unit, the mask plate pick-up and placement hand Z-axis movement unit, the mask plate pick-up and placement hand R-axis movement unit, and the mask plate pick-up and placement fork to move along the X-axis.

[0013] Further, the internal mask plate library unit includes a plurality of internal mask plate library modules, and each internal mask plate library template is configured to store multiple mask plates.

[0014] Further, the mask transfer system further includes a support frame, which includes an upper space and a lower space; the inner magazine unit includes a plurality of inner magazine modules, and the plurality of inner magazine modules are arranged at intervals in the lower space of the support frame along the X-axis direction; the outer magazine unit is installed on the outside of the support frame along the X-axis direction close to the lower space of the support frame; the pick-and-place unit is arranged in the lower space of the support frame and is arranged opposite to the inner magazine unit along the Y-axis direction; the buffer table unit is installed in the lower space of the support frame, and the buffer table unit includes an upper plate buffer table and a lower plate buffer table, and the upper plate buffer table is on the same straight line as the pre-alignment station along the Y-axis direction; the pre-alignment unit is arranged on the outside of the support frame along the Y-axis direction and is close to the buffer table unit; the exchange hand unit includes an exchange hand frame, and the exchange hand unit is installed in the upper space of the support frame through the exchange hand frame.

[0015] The present invention also provides a method for transferring a mask plate, which uses the mask transfer system described above to transfer the mask plate, and includes the following steps:

[0016] S1: Load the mask plate cassette at the man-machine interface station, and the outer magazine unit transfers the mask plate cassette at the man-machine interface station to the first handover station and opens the mask plate cassette;

[0017] S2: The pick-and-place unit moves to the first handover station, takes out the mask plate from the opened mask plate cassette, and transfers it to the inner magazine unit, and the inner magazine unit stores and manages the mask plate;

[0018] S3: The pick-and-place unit moves to the inner magazine unit, takes out the mask plate, and transfers it to the buffer table unit;

[0019] S4: The mask plate grasping and placing positioning mechanism of the exchange hand unit moves to the buffer table unit and grasps the mask plate;

[0020] S5: The exchange hand R-axis movement unit drives the mask plate grasping and placing positioning mechanism to rotate a specified angle to meet the requirements of the mask plate exposure pattern layout design; the mask plate grasping and placing positioning mechanism drives the mask plate to move to the mask table handover station, and the exchange hand Z-axis movement unit drives the mask plate grasping and placing positioning mechanism to descend into the mask table, and the mask plate grasping and placing positioning mechanism releases the mask plate and mounts the mask plate onto the mask table;

[0021] S6: After the exposure is completed, the reticle stage transfers the reticle to the reticle stage handover station. The reticle gripper positioning mechanism moves to the reticle stage handover station. The Z-axis movement unit of the exchange plate hand drives the reticle gripper positioning mechanism to descend into the reticle stage. The reticle gripper positioning mechanism grabs the reticle in the reticle stage, and then the Z-axis movement unit of the exchange plate hand drives the reticle gripper positioning mechanism to rise to complete the grasping of the reticle in the reticle stage.

[0022] S7: The exchange plate hand unit drives the reticle to move and transfers the reticle to the buffer stage unit.

[0023] S8: The pick-and-place plate hand unit moves to the buffer stage unit, takes out the reticle, and transfers the reticle to the inner reticle library unit.

[0024] S9: The pick-and-place plate hand unit moves to the inner reticle library unit, takes out the reticle, and transfers the reticle to the first handover station.

[0025] S10: The outer reticle library unit transfers the reticle at the first handover station to the reticle cassette at the human-machine interface station.

[0026] Further, between S4 and S5, it further includes:

[0027] Pre-alignment operation of the reticle: The reticle gripper positioning mechanism drives the reticle to move to the pre-alignment station. The pre-alignment unit identifies the alignment marks of the reticle, obtains the position deviation generated during the reticle transfer process, and the exchange plate hand unit adjusts the position of the reticle according to the position deviation.

[0028] The present invention also provides a lithography apparatus including the reticle transfer system described above.

[0029] Compared with the prior art, the reticle transfer system, transfer method, and lithography apparatus provided by the present invention have the following advantages:

[0030] In the reticle transfer system of the present invention, the reticle gripper positioning mechanism drives the reticle to achieve 4 degrees of freedom of movement, including planar movement in the X and Y directions, vertical lifting movement in the Z direction, and rotation of the reticle gripper positioning mechanism around the Rz axis. Thus, the reticle gripper positioning mechanism of the exchange plate hand unit can perform the operation of reaching into the reticle stage to pick up and place the reticle, and is applicable to the reticle transfer scenario of the "embedded reticle" in a large field of view and high NA objective lens exposure machine.

[0031] The present invention adds a buffer table unit, dividing the two major functions of the reticle transfer system, namely reticle transfer and storage management of reticles, into an internal and an external loop. Among them, the external loop process is as follows: The reticle is circulated among the human-machine interface station, the external reticle library unit, the internal reticle library unit, and the buffer table unit through the external reticle library unit and the pick-and-place hand unit. The internal loop process is as follows: The movement of the exchange hand unit drives the reticle to circulate among the buffer table unit, the pre-alignment unit, and the reticle stage. In this way, the distance for loading and unloading the reticle on the reticle stage can be shortened, improving the positioning accuracy and stability of the reticle handover with the reticle stage, thereby increasing the reticle loading and unloading productivity and the loading repeatability.

[0032] The buffer table unit of the present invention includes an upper plate buffer table and a lower plate buffer table. The upper plate buffer table temporarily stores the reticle required for exposure, and the lower plate buffer table temporarily stores the reticle after exposure. In this way, when a reticle is being used during the exposure process, the pick-and-place hand unit does not need to wait for the exposure to complete to unload the reticle. Instead, it can directly pick up the reticle required for the next exposure and temporarily store it on the upper plate buffer table. After the current exposure process is completed, the exchange hand unit can pick up the reticle after the current exposure and directly store it on the lower plate buffer table. And after the unloading is completed, it can immediately pick up the reticle required for the next exposure from the upper plate buffer table and enter the loading process. The pick-and-place hand unit can also directly pick up the reticle after exposure from the lower plate buffer table and transfer it to the internal reticle library unit for storage. In this way, through the setting of the two buffer tables, the pick-and-place hand unit and the exchange hand unit can work continuously without interference, improving the overall transfer efficiency of the reticle and the exposure efficiency.

[0033] The pick-and-place fork in the pick-and-place hand unit of the present invention can also achieve 4 degrees of freedom of movement, including planar movement in the X and Y directions, vertical lifting movement in the Z direction, and rotation of the pick-and-place fork around the Rz axis. The multi-degree-of-freedom movement makes it more convenient for the pick-and-place hand unit to pick up, place, and transfer the reticle among the first handover station, the internal reticle library unit, and the buffer table unit.

[0034] The internal reticle library unit of the present invention includes multiple internal reticle library modules. Through expansion, the storage management capacity of the reticle can be increased from 6 - 18 pieces in the prior art to 30 pieces or more, which can meet the storage management requirements of more reticles in the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of the reticle transfer system in an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of the lower layer structure of the reticle transfer system in an embodiment of the present invention;

[0037] Figure 3Schematic diagram of the upper structure of a mask transfer system in an embodiment of the present invention;

[0038] Figure 4 Schematic diagram of the "embedded mask" of a large field high-NA objective exposure machine in an embodiment of the present invention;

[0039] Figure 5 Schematic diagram of a mask gripper positioning mechanism gripping a mask in an embodiment of the present invention;

[0040] Figure 6 and Figure 7 Schematic diagram of the flow process of a mask in a mask transfer method in an embodiment of the present invention;

[0041] Wherein, the reference numerals are as follows:

[0042] 10 - Outer mask library unit; 20 - Inner mask library unit; 30 - Buffer table unit; 40 - Mask pick-and-place unit; 50 - Mask exchange unit; 60 - Pre-alignment unit; 70 - Support frame; 11 - Outer mask library lifting assembly; 12 - Mask cassette carrying assembly; 31 - Upper mask buffer table; 32 - Lower mask buffer table; 41 - Mask pick-and-place fork; 42 - Mask pick-and-place hand R-axis movement unit; 43 - Mask pick-and-place hand Z-axis movement unit; 44 - Mask pick-and-place hand X-axis movement unit; 45 - Mask pick-and-place hand Y-axis movement unit; 51 - Mask gripper positioning mechanism; 511 - Fork body; 512 - Positioning component; 52 - Mask exchange hand R-axis movement unit; 53 - Mask exchange hand Z-axis movement unit; 54 - Mask exchange hand X-axis movement unit; 55 - Mask exchange hand Y-axis movement unit; 56 - Mask exchange hand frame. Detailed implementation manners

[0043] The following further elaborates on a mask transfer system, a transfer method, and a lithography apparatus proposed by the present invention in conjunction with the accompanying drawings and specific implementation manners. According to the following description, the advantages and features of the present invention will be clearer.

[0044] It should be noted that the accompanying drawings are in a very simplified form and all use non-precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features, and advantages of the present invention more obvious and understandable, please refer to the accompanying drawings. It should be known that the structures, scales, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they do not have technical essence. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed by the present invention.

[0045] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0046] In this article, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element. The methods described herein include a series of steps, and the order of these steps presented herein is not necessarily the only order in which these steps can be executed, and some of the described steps may be omitted and / or some other steps not described herein may be added to the method.

[0047] The core idea of the present invention is to provide a mask transfer system, a transfer method and a lithography apparatus to solve the problem of mask transfer for a large field of view and high NA objective lens exposure machine in the prior art.

[0048] Embodiment 1

[0049] Such as Figures 1 to 3As shown, the present invention provides a mask transmission system, including an external plate library unit 10, an internal plate library unit 20, a buffer unit 30, a plate pick-up and placement hand unit 40 and a plate exchange hand unit 50; the external plate library unit 10 is configured to receive the mask and transfer the mask to a first handover station, and the first handover station is a position where the external plate library unit 10 and the plate pick-up and placement hand unit 40 hand over the mask; the internal plate library unit 20 is configured to store the mask; the buffer unit 30 is configured to temporarily store the mask; the plate pick-up and placement hand unit 40 is configured to pick up, place and transfer the mask between the first handover station, the internal plate library unit 20 and the buffer unit 30; the plate exchange hand unit 50 includes: a mask pick-up and placement positioning mechanism 51, an exchange plate The plate hand R-axis motion unit 52, the plate exchange hand Z-axis motion unit 53, the plate exchange hand X-axis motion unit 54, and the plate exchange hand Y-axis motion unit 55; the plate exchange hand R-axis motion unit 52 is configured to drive the mask plate grasping and placing positioning mechanism 51 to rotate; the plate exchange hand Z-axis motion unit 53 is configured to drive the mask plate grasping and placing positioning mechanism 51 to move up and down along the Z axis; the plate exchange hand X-axis motion unit 54 is configured to drive the mask plate grasping and placing positioning mechanism 51 to move along the X axis; the plate exchange hand Y-axis motion unit 55 is configured to drive the mask plate grasping and placing positioning mechanism 51 to move along the Y axis; the plate exchange hand unit 50 is configured to pick up, place and transfer the mask between the cache table unit 30 and the mask table (not shown in the figure).

[0050] Please refer to Figure 4 The figure shows a schematic diagram of the "embedded mask" of a large field of view high NA objective lens exposure machine. To meet the needs of high-end process applications, exposure machines require higher resolution, larger exposure field of view, higher overlay accuracy, etc. This is also the development trend of the exposure machine market. Large field of view high NA objective lens exposure machines have a small working distance (i.e. Figure 4 The distance h between the object plane and the objective lens shown in the figure, the mask stage generally adopts an "embedded mask" design, so the mask handover method of the existing technology "clamping and flat dragging" cannot be applied to this scenario.

[0051] In the scheme of the present invention, Figure 3 and Figure 5 As shown, the mask pick-and-place positioning mechanism 51 drives the mask to realize 4 degrees of freedom, including planar motion along the X and Y directions, vertical lifting motion along the Z direction, and Rz axial rotation of the mask pick-and-place positioning mechanism 51. In this way, the mask pick-and-place positioning mechanism 51 of the mask exchange hand unit can be extended into the mask stage to perform the operation of picking up and placing the mask, which can be applied to the mask transmission scenario of the "embedded mask" of the large field of view high NA objective lens exposure machine.

[0052] In addition, the present invention adds a buffer unit 30, which divides the two major functions of the mask transmission system: mask transmission and mask storage management into two internal and external loops. Figure 5 andFigure 6 As shown in the figure, the outer loop process is as follows: The mask is circulated among the man-machine interface station, the outer mask library unit 10, the inner mask library unit 20, and the buffer table unit 30 through the outer mask library unit 10 and the pick-and-place mask hand unit 40. The inner loop process is as follows: The movement of the mask exchange hand unit 50 drives the mask to circulate between the buffer table unit 30 and the mask table. In this way, the distance for loading and unloading the mask on the mask table can be shortened, the positioning accuracy and stability of transferring the mask 80 with the mask table are improved, thereby improving the mask loading and unloading productivity and the repeatability of loading the mask.

[0053] In the above solution, as Figure 3 shown, the mask gripper positioning mechanism 51 is rotatably installed on the R-axis movement unit 52 of the mask exchange hand, and the R-axis movement unit 52 of the mask exchange hand can drive the mask gripper positioning mechanism 51 to rotate; the R-axis movement unit 52 of the mask exchange hand is movably installed on the Z-axis movement unit 53 of the mask exchange hand, and the Z-axis movement unit 53 of the mask exchange hand can drive the R-axis movement unit 52 of the mask exchange hand and the mask gripper positioning mechanism 51 to move up and down along the Z-axis; the Z-axis movement unit 53 of the mask exchange hand is movably installed on the X-axis movement unit 54 of the mask exchange hand, and the X-axis movement unit 54 of the mask exchange hand can drive the Z-axis movement unit 53 of the mask exchange hand, the R-axis movement unit 52 of the mask exchange hand, and the mask gripper positioning mechanism 51 to move along the X-axis; the X-axis movement unit 54 of the mask exchange hand is movably installed on the Y-axis movement unit 55 of the mask exchange hand, and the Y-axis movement unit 55 of the mask exchange hand can drive the X-axis movement unit 54 of the mask exchange hand, the Z-axis movement unit 53 of the mask exchange hand, the R-axis movement unit 52 of the mask exchange hand, and the mask gripper positioning mechanism 51 to move along the Y-axis. Thus, the R-axis movement unit 52 of the mask exchange hand, the Z-axis movement unit 53 of the mask exchange hand, the X-axis movement unit 54 of the mask exchange hand, and the Y-axis movement unit 55 of the mask exchange hand can drive the mask gripper positioning member mechanism 51 to move, and the mask gripper positioning mechanism 51 can drive the mask to move in 4 degrees of freedom, so as to complete the picking, placing, and transferring of the mask between the buffer table unit 30 and the mask table. Of course, those skilled in the art can understand that the components in the mask exchange hand unit 50 can also adopt other connection methods. For example, by changing the connection relationship between the movement units. In the above solution, the Y-axis movement unit 55 of the mask exchange hand is installed on the X-axis movement unit 54 of the mask exchange hand, and the Z-axis movement unit 53 of the mask exchange hand is installed on the Y-axis movement unit 55 of the mask exchange hand, and the free movement of the mask gripper positioning mechanism 51 can also be realized. The present invention does not strictly limit the connection relationship between the components, as long as the free movement of the mask gripper positioning mechanism 51 in 4 degrees of freedom can be realized, it belongs to the protection scope of the present invention.

[0054] In an embodiment of the present invention, the mask handling and positioning mechanism 51 may include a mask fork body 511 and a positioning component 512. The mask fork body 511 is rotatably mounted on the R-axis movement unit 52 of the mask exchanger hand, and the positioning component 512 is mounted on the mask fork body 511. Among them, the positioning component 512 may include a positioning part and a driving part. The positioning part is movably arranged on the lower surface of the mask fork body 511, and the driving part is connected to the positioning part and is configured to drive the positioning part to move.

[0055] Optionally, the number of the positioning components 512 may be set to four, two of which are X-direction positioning components and the other two are Y-direction positioning components; the two X-direction positioning components are arranged along the X direction, and the moving direction of the positioning part of the X-direction positioning component is the X direction; the two Y-direction positioning components are arranged along the Y direction, and the moving direction of the positioning part of the Y-direction positioning component is the Y direction; the Y direction is perpendicular to the X direction, and the connection line of the two X-direction positioning components intersects with the connection line of the two Y-direction positioning components.

[0056] In this way, through the movement of the positioning parts of the respective positioning components 512, the mask handling and positioning mechanism 51 can grasp or release the mask, and thus can pick and place the mask at a specified position (such as the mask table).

[0057] As an embodiment of the present invention, the mask transfer system may further include a pre-alignment unit 60. The pre-alignment unit 60 is configured to identify the alignment marks of the mask 80 and obtain the position deviation generated during the transfer of the mask 80; the mask exchanger hand unit 50 is configured to pick, place and transfer the mask between the buffer table unit 30, the pre-alignment unit 60 and the mask table. At this time, in the inner loop process, the movement of the mask exchanger hand unit 50 can drive the mask to circulate among the buffer table unit 30, the pre-alignment unit 60 and the mask table. The pre-alignment unit 60 can realize the pre-alignment of the mask. Before the mask exchanger hand unit 50 drives the mask to be transferred onto the mask table, the mask can be first transferred to the pre-alignment station, and the pre-alignment unit 60 is used to identify the alignment marks of the mask 80, so that the position deviation generated by the mask during the transfer of the mask can be judged. According to this position deviation, the mask handling and positioning mechanism 51 is driven to move by the R-axis movement unit 52, the Z-axis movement unit 53, the X-axis movement unit 54 and the Y-axis movement unit 55 of the mask exchanger hand, so as to realize the position adjustment of the mask 80 and ensure the upper plate accuracy of the mask 80 before it is handed over to the mask table.

[0058] As a preferred embodiment of the present invention, the buffer table unit 30 includes an upper mask buffer table 31 and a lower mask buffer table 32. The upper mask buffer table 31 is configured to temporarily store the mask required for exposure; the lower mask buffer table 32 is configured to temporarily store the mask after the exposure is completed. In this way, when a mask is being used during the exposure process, the mask handling unit 40 does not need to wait for the mask that has been used in the exposure process to be unloaded. Instead, it can directly grab the mask required for the next exposure and temporarily store it on the upper mask buffer table 31. After the current exposure process is completed, the mask exchanging unit 50 can grab the mask that has been used in the exposure process and directly store it on the lower mask buffer table 32. And after the unloading is completed, it can immediately grab the mask required for the next exposure from the upper mask buffer table 31 and enter the upper loading process. The mask handling unit 40 can also directly grab the mask that has been used in the exposure process from the lower mask buffer table 31 and transfer it to the inner mask library unit 20 for storage. In this way, through the setting of the two buffer tables, the mask handling unit 40 and the mask exchanging unit 50 can work continuously without interference, improving the overall transfer efficiency and exposure efficiency of the mask.

[0059] Exemplarily, as Figure 2 shown, the mask handling unit 40 may include a mask handling fork 41, a mask handling hand R-axis movement unit 42, a mask handling hand Z-axis movement unit 43, a mask handling hand X-axis movement unit 44, and a mask handling hand Y-axis movement unit 45; the mask handling hand R-axis movement unit 42 is configured to drive the mask handling fork 41 to rotate; the mask handling hand Z-axis movement unit 43 is configured to drive the mask handling fork 41 to move up and down along the Z-axis; the mask handling hand X-axis movement unit 44 is configured to drive the mask handling fork 41 to move along the X-axis; the mask handling hand Y-axis movement unit 45 is configured to drive the mask handling fork 41 to move along the Y-axis. Through the above settings, the mask handling fork 41 can achieve movement in 4 degrees of freedom, namely rotation around its own axis and movement along the X-axis, Y-axis, and Z-axis, so as to pick up and transfer the mask between the first transfer station, the inner mask library unit 20, and the buffer table unit 30.

[0060] As an implementation solution of the present invention, in the plate picking and placing hand unit 40, the plate picking and placing fork 41 is rotatably installed on the plate picking and placing hand R-axis movement unit 42, and the plate picking and placing hand R-axis movement unit 42 can drive the plate picking and placing fork 41 to rotate; the plate picking and placing hand R-axis movement unit 42 is installed on the plate picking and placing hand Z-axis movement unit 43, and the plate picking and placing hand Z-axis movement unit 43 can drive the plate picking and placing hand R-axis movement unit 42 and the plate picking and placing fork 41 to move up and down along the Z-axis; the plate picking and placing hand Z-axis movement unit 43 is installed on the plate picking and placing hand Y-axis movement unit 45, and the plate picking and placing hand Y-axis movement unit 45 can drive the plate picking and placing hand Z-axis movement unit 43, the plate picking and placing hand R-axis movement unit 42 and the plate picking and placing fork 41 to move along the Y-axis; the plate picking and placing hand Y-axis movement unit 45 is installed on the plate picking and placing hand X-axis movement unit 44, and the plate picking and placing hand X-axis movement unit 44 can drive the plate picking and placing hand Y-axis movement unit 45, the plate picking and placing hand Z-axis movement unit 43, the plate picking and placing hand R-axis movement unit 42 and the plate picking and placing fork 41 to move along the X-axis. In this way, the plate picking and placing fork 41 can realize movements in 4 degrees of freedom, namely along the X-axis, Y-axis, Z-axis and its own rotation. Of course, those skilled in the art can understand that the components in the plate picking and placing hand unit 40 can also adopt other connection methods. For example, by changing the connection relationship between the movement units. In the above solution, the plate picking and placing hand X-axis movement unit 44 is installed on the plate picking and placing hand Y-axis movement unit 45, and the plate picking and placing hand Z-axis movement unit 43 is installed on the plate picking and placing hand X-axis movement unit 44, and the free movement of the plate picking and placing fork 41 can also be realized. The present invention does not strictly limit the connection relationship between the components, as long as the free movement of the plate picking and placing fork 41 in 4 degrees of freedom can be realized, it belongs to the protection scope of the present invention.

[0061] Preferably, the inner mask library unit 20 includes a plurality of inner mask library modules, and each inner mask library template is configured to store multiple mask plates. For example, the inner mask library unit may include 5 inner mask library modules, and each inner mask library template is configured to store at least 6 mask plates. In this way, through expansion, the storage management capacity of the mask plates is increased from 6 - 18 in the prior art to 30, which can meet the storage management requirements of more mask plates in the market. Of course, those skilled in the art can understand that the number of inner mask library modules can be set according to the remaining space and requirements in the actual mask plate transmission system.

[0062] In an embodiment of the present invention, the external magazine unit 10 may include an external magazine lifting assembly 11 and a cassette carrier assembly 12; the external magazine lifting assembly 11 is configured to drive the cassette carrier assembly 12 to move up and down between the human-machine interface station and the first transfer station; the cassette carrier assembly 12 is configured to identify and manage the reticle cassette and the reticle, as well as open and close the reticle cassette. Generally, the human-machine interface station may be set at the lowest position of the lifting movement of the cassette carrier assembly 12, and the first transfer station may be set at the highest position of the lifting movement of the cassette carrier assembly 12. A dedicated sensor is provided at the position corresponding to the human-machine interface station on the external magazine lifting assembly 11 to detect information such as the material information, presence, and position status of the reticle cassette and the reticle. When the operator places the reticle cassette at the human-machine interface station, the sensor will detect the relevant information, trigger the external magazine lifting assembly 11 to drive the cassette carrier assembly 12 to move downward to the human-machine interface station, and then the cassette carrier assembly 12 grabs the reticle cassette. The external magazine lifting assembly 11 then drives the cassette carrier assembly 12 to move upward. A corresponding in-place detection sensor is also provided at the position corresponding to the first transfer station on the external magazine lifting assembly 11. When the cassette carrier assembly 12 drives the reticle cassette to move to the first transfer station, the corresponding in-place detection sensor will be triggered. A cassette unlocking assembly is provided inside the cassette carrier assembly 12, which can unlock the reticle cassette and open the reticle cassette. Corresponding sensors for detecting and identifying the reticle cassette and the reticle are also provided inside the cassette carrier assembly 12, which can detect and identify the information of the reticle cassette and the reticle. For example, a dedicated sensor for detecting whether the reticle is a relief plate is provided inside the cassette carrier assembly 12. When it is detected that the reticle inside the reticle cassette is a relief plate, it indicates that the reticle is in an incorrect position, and the subsequent plate handling unit 40 will not be able to pick up the plate normally from the reticle cassette. At this time, the subsequent operation will be stopped and an alarm will be triggered to remind the staff to check the status of the reticle. Only when the reticle cassette is opened and the sensors inside the cassette carrier assembly 12 detect normally, the plate handling unit 40 will pick up the plate from the reticle cassette at the first transfer station for the subsequent transfer process. Among them, the identification and management of the reticle cassette and the reticle by the cassette carrier assembly 12, as well as the opening and closing of the reticle cassette, have similar solutions in the prior art, and the present invention will not elaborate on this here.

[0063] In an embodiment of the present invention, a support frame 70 may be provided, and the internal magazine unit 20, the buffer table unit 30, the plate handling unit 40, and the plate exchange unit 50 are all installed on the support frame 70, making the integration degree of the entire reticle transmission system higher, improving the structural stability of each component, and making the movement of the plate handling unit 40 and the plate exchange unit 50 more stable. In addition, the external magazine unit 10 and the pre-alignment unit 60 may also be integrally installed on the support frame 70.

[0064] Specifically, as Figures 1 to 3 shown, the components in the mask transfer system of the present invention can be roughly divided into a two-layer structure. The outer library unit 10, the inner library unit 20, the buffer table unit 30, the pick-and-place unit 40, and the pre-alignment unit 60 are located in the lower layer, and the exchange unit 50 is installed in the upper layer.

[0065] Among them, the support frame 70 can include an upper space and a lower space. A plurality of inner library modules of the inner library unit 20 are arranged at intervals in the X-axis direction in the lower space of the support frame 70; the outer library unit 10 is installed outside the support frame 70 along the X-axis direction close to the lower space of the support frame 70; the pick-and-place unit 40 is arranged in the lower space of the support frame 70 and is arranged opposite to the inner library unit 20 in the Y-axis direction to facilitate the pick-and-place unit 40 to pick up and place the mask from the inner library unit 20; the buffer table unit 30 is installed in the lower space of the support frame 70, and the upper plate buffer table 31 of the buffer table unit 30 is generally in the same straight line as the pre-alignment station in the Y-axis direction to minimize the movement distance when loading the mask; the pre-alignment unit 60 is arranged outside the support frame 70 in the Y-axis direction and is close to the buffer table unit 30; the exchange unit 50 includes an exchange frame 56. The exchange unit 50 is installed in the upper space of the support frame 70 through the exchange frame 56, that is, the exchange unit 50 is separately installed in the upper layer of the support frame 70. For example, the exchange frame 56 is installed on the support frame 70, and other components of the exchange unit 50 are installed on the exchange frame 56. In this way, the exchange unit 50 can more conveniently grab the mask to realize the lifting movement in the vertical direction, facilitating the handover of the mask between the exchange unit 50 and the mask table.

[0066] The present invention also provides a lithography apparatus, including the above mask transfer system.

[0067] Embodiment 2

[0068] The present invention also provides a method for transferring a mask, using the mask transfer system provided in Embodiment 1 to transfer the mask. As Figures 5 to 6 shown in the schematic diagram of the mask loading and unloading process of the mask, the transfer method includes the following steps:

[0069] S1: Load the reticle cassette at the man-machine interface station. The external cassette storage unit transports the reticle cassette at the man-machine interface station to the first transfer station and opens the reticle cassette. Before the reticle loading process, the reticle transfer system is in the initialization state. The operator can open the overall protection door of the lithography equipment at the man-machine interface position, perform the operation of placing the reticle cassette, and after correctly placing the reticle cassette, close the overall protection door of the lithography equipment. At this time, the external cassette storage unit 10 detects the material information, presence, and position status of the reticle cassette and reticle through the corresponding sensors, and then the external cassette storage unit 10 transports the reticle cassette at the man-machine interface station to the first transfer station and opens the reticle cassette;

[0070] S2: The reticle pick-and-place unit moves to the first transfer station, takes out the reticle from the opened reticle cassette, and transports it to the internal cassette storage unit. The reticle pick-and-place unit can load the reticle into the designated empty cassette slot of the internal cassette storage unit, and the internal cassette storage unit manages the storage of the reticle;

[0071] S3: The reticle pick-and-place unit moves to the internal cassette storage unit, takes out the reticle, and transports it to the buffer table unit; specifically, the buffer table unit can include a loading buffer table and an unloading buffer table. During the loading operation, the reticle pick-and-place unit transports and loads the reticle onto the loading buffer table;

[0072] S4: The reticle gripper positioning mechanism of the reticle exchange unit moves to the buffer table unit and grabs the reticle; during the process of loading the reticle onto the reticle stage, it is realized through the reticle exchange unit. The reticle gripper positioning mechanism grabs the reticle from the loading buffer table and then transports the reticle to the reticle stage. Preferably, before transporting the reticle to the reticle stage, a pre-alignment operation is also required. The pre-alignment operation includes: the reticle gripper positioning mechanism drives the reticle to move to the pre-alignment station, the pre-alignment unit identifies the alignment marks of the reticle, obtains the position deviation generated during the reticle transmission process, and the reticle exchange unit adjusts the position of the reticle according to the position deviation to ensure the loading accuracy of the reticle before it is transferred to the reticle stage.

[0073] S5: The reticle exchange unit's R-axis movement unit drives the reticle gripper positioning mechanism to rotate a specified angle, generally 90 degrees clockwise, to meet the requirements of the reticle exposure pattern layout design; the reticle gripper positioning mechanism drives the reticle to move to the reticle stage transfer station, and the reticle exchange unit's Z-axis movement unit drives the reticle gripper positioning mechanism to descend into the reticle stage. The reticle gripper positioning mechanism releases the reticle and loads the reticle onto the reticle stage; in the solution of the present invention, the reticle gripper positioning mechanism extends into the reticle stage to perform the reticle loading operation, which can adapt to the reticle transmission scenario of a large-field high-NA objective exposure machine.

[0074] S6: After the exposure is completed, the reticle stage transports the reticle to the reticle stage handover station. The reticle gripper positioning mechanism moves to the reticle stage handover station. The Z-axis movement unit of the exchange hand drives the reticle gripper positioning mechanism to descend into the reticle stage. The reticle gripper positioning mechanism grabs the reticle in the reticle stage, and then the Z-axis movement unit of the exchange hand drives the reticle gripper positioning mechanism to rise to complete the grasping of the reticle in the reticle stage.

[0075] S7: The exchange hand unit drives the reticle to move and transports the reticle to the buffer stage unit; during the reticle unloading operation, each movement unit of the exchange hand unit can drive the reticle gripper positioning mechanism to move, grab the reticle after the exposure is completed from the reticle stage and transport it to the lower reticle buffer stage, and then the reticle gripper positioning mechanism moves to the upper reticle buffer stage to prepare to grab the reticle required for the next exposure for the next reticle loading operation.

[0076] S8: The reticle pick-and-place hand unit moves to the buffer stage unit, takes out the reticle, and transports the reticle to the internal reticle library unit; after the reticle pick-and-place hand unit takes out the reticle from the lower reticle buffer stage, it can directly transport it to the designated empty slot in the internal reticle library unit to store the reticle after the exposure is completed.

[0077] S9: The reticle pick-and-place hand unit moves to the internal reticle library unit, takes out the reticle, and transports the reticle to the first handover station; when taking out the reticle after the exposure is completed from the lithography equipment, the reticle pick-and-place hand unit takes out the reticle from the designated slot in the internal reticle plate and transports it to the first handover station.

[0078] S10: The external reticle library unit transports the reticle at the first handover station to the reticle cassette at the human-machine interface station, thus completing the reticle unloading operation.

[0079] In summary, compared with the prior art, the reticle transfer system, transfer method, and lithography equipment provided by the present invention have the following advantages:

[0080] In the reticle transfer system of the present invention, the reticle gripper positioning mechanism drives the reticle to achieve 4 degrees of freedom of movement, including planar movement in the X and Y directions, vertical lifting movement in the Z direction, and rotation of the reticle gripper positioning mechanism around the Rz axis. Thus, the reticle gripper positioning mechanism of the exchange hand unit can achieve the operation of reaching into the reticle stage to pick and place the reticle, and can be applied to the reticle transfer scenario of the "embedded reticle" of a large field-of-view high-NA objective exposure machine.

[0081] The present invention adds a buffer station unit, and divides the two major functions of the mask transmission system: mask transmission and mask storage management into two internal and external loops. Among them, the external loop process is: through the external plate library unit and the plate pick-and-place hand unit, the mask plate is realized The mutual circulation between the human-machine interface station, the external plate library unit, the internal plate library unit and the buffer station unit. The internal loop process is: through the movement of the plate exchange hand unit, the mask plate is driven to circulate between the buffer station unit, the pre-alignment unit and the mask station. In this way, the distance for the mask plate to be loaded and unloaded on the mask table can be shortened, and the positioning accuracy and stability of the mask plate handed over to the mask table are improved, thereby improving the mask loading and unloading yield and the plate loading repeatability.

[0082] The buffer table unit of the present invention includes an upper plate buffer table and a lower plate buffer table. The upper plate buffer table temporarily stores the mask plate required for exposure, and the lower plate buffer table temporarily stores the mask plate after exposure. In this way, when a mask plate is used during the exposure process, the plate pick-up and placement hand unit does not need to wait for the mask plate to be removed after the exposure is completed, and can directly grab the mask plate required for the next exposure and temporarily store it in the upper plate buffer table. After the current exposure process is completed, the plate exchange hand unit can grab the mask plate after the current exposure is completed and directly temporarily store it in the lower plate buffer table, and after the plate is removed, the mask plate required for the next exposure can be grabbed from the upper plate buffer table to enter the plate loading process, and the plate pick-up and placement hand unit can also directly grab the mask plate after exposure from the lower plate buffer table and transfer it to the internal plate library unit for storage. In this way, through the setting of the two buffer tables, the plate pick-up and placement hand unit and the plate exchange hand unit can continue to work without interfering with each other, thereby improving the overall transmission efficiency and exposure efficiency of the mask plate.

[0083] The plate picking and placing fork in the plate picking and placing hand unit of the present invention can also realize four degrees of freedom of movement, including planar movement along the X and Y directions, vertical lifting movement along the Z direction, and Rz axial rotation of the plate picking and placing fork. The multi-degree-of-freedom movement makes it more convenient for the plate picking and placing hand unit to pick up, place and transfer the mask between the first handover station, the internal plate library unit and the cache unit.

[0084] The inner plate library unit of the present invention includes multiple inner plate library modules, and can increase the storage management capacity of mask plates from 6-18 blocks in the prior art to 30 blocks or even more through expansion, which can meet the storage management needs of more mask plates in the market.

[0085] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention based on the above disclosure fall within the scope of protection of the claims. Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A mask transfer system, characterized in that, It includes an external mask library unit, an internal mask library unit, a buffer table unit, a mask handling unit, and a mask exchange unit; The external mask library unit is configured to receive a mask and transfer the mask to the first handover station; The internal mask library unit is configured to store masks; The buffer table unit is configured to temporarily store masks; The mask handling unit is configured to pick up, place, and transfer masks between the first handover station, the internal mask library unit, and the buffer table unit; The mask exchange unit includes: a mask grasping, placing, and positioning mechanism, a mask exchange R-axis movement unit, a mask exchange Z-axis movement unit, a mask exchange X-axis movement unit, and a mask exchange Y-axis movement unit; The mask exchange R-axis movement unit is configured to drive the mask grasping, placing, and positioning mechanism to rotate; the mask exchange Z-axis movement unit is configured to drive the mask grasping, placing, and positioning mechanism to move up and down along the Z-axis; the mask exchange X-axis movement unit is configured to drive the mask grasping, placing, and positioning mechanism to move along the X-axis; the mask exchange Y-axis movement unit is configured to drive the mask grasping, placing, and positioning mechanism to move along the Y-axis; The mask exchange unit is configured to pick up, place, and transfer masks between the buffer table unit and the mask table; 2. The mask transfer system according to claim 1, wherein The mask grasping, placing, and positioning mechanism is rotatably mounted on the mask exchange R-axis movement unit, the mask exchange R-axis movement unit is movably mounted on the mask exchange Z-axis movement unit, the mask exchange Z-axis movement unit is movably mounted on the mask exchange X-axis movement unit, and the mask exchange X-axis movement unit is movably mounted on the mask exchange Y-axis movement unit; The mask exchange R-axis movement unit is configured to drive the mask grasping, placing, and positioning mechanism to rotate; The mask exchange Z-axis movement unit is configured to drive the mask exchange R-axis movement unit and the mask grasping, placing, and positioning mechanism to move up and down along the Z-axis; The mask exchange X-axis movement unit is configured to drive the mask exchange Z-axis movement unit, the mask exchange R-axis movement unit, and the mask grasping, placing, and positioning mechanism to move along the X-axis; The mask exchange Y-axis movement unit is configured to drive the mask exchange X-axis movement unit, the mask exchange Z-axis movement unit, the mask exchange R-axis movement unit, and the mask grasping, placing, and positioning mechanism to move along the Y-axis.

3. The mask transfer system according to claim 1, wherein It further includes a pre-alignment unit, which is configured to identify the alignment marks of the mask and obtain the position deviation generated during the mask transfer process; The mask exchange unit is configured to pick up, place, and transfer masks between the buffer table unit, the pre-alignment unit, and the mask table; 4. The mask transfer system according to claim 1, wherein The buffer table unit includes an upper mask buffer table and a lower mask buffer table, The upper mask buffer table is configured to temporarily store the masks required for exposure; The lower mask buffer table is configured to temporarily store the masks after the exposure is completed; 5. The mask transfer system according to claim 1, wherein The mask handling unit includes a mask handling fork, a mask handling R-axis movement unit, a mask handling Z-axis movement unit, a mask handling X-axis movement unit, and a mask handling Y-axis movement unit; The R-axis movement unit of the pick-and-place plate hand is configured to drive the pick-and-place plate fork to rotate; the Z-axis movement unit of the pick-and-place plate hand is configured to drive the pick-and-place plate fork to move up and down along the Z-axis; The X-axis movement unit of the pick-and-place plate hand is configured to drive the pick-and-place plate fork to move along the X-axis; the Y-axis movement unit of the pick-and-place plate hand is configured to drive the pick-and-place plate fork to move along the Y-axis.

6. The mask transfer system according to claim 5, characterized in that, The pick-and-place plate fork is rotatably mounted on the R-axis movement unit of the pick-and-place plate hand, the R-axis movement unit of the pick-and-place plate hand is movably mounted on the Z-axis movement unit of the pick-and-place plate hand, the Z-axis movement unit of the pick-and-place plate hand is movably mounted on the Y-axis movement unit of the pick-and-place plate hand, and the Y-axis movement unit of the pick-and-place plate hand is movably mounted on the X-axis movement unit of the pick-and-place plate hand; The R-axis movement unit of the pick-and-place plate hand is configured to drive the pick-and-place plate fork to rotate; The Z-axis movement unit of the pick-and-place plate hand is configured to drive the R-axis movement unit of the pick-and-place plate hand and the pick-and-place plate fork to move up and down along the Z-axis; The Y-axis movement unit of the pick-and-place plate hand is configured to drive the Z-axis movement unit of the pick-and-place plate hand, the R-axis movement unit of the pick-and-place plate hand and the pick-and-place plate fork to move along the Y-axis; The X-axis movement unit of the pick-and-place plate hand is configured to drive the Y-axis movement unit of the pick-and-place plate hand, the Z-axis movement unit of the pick-and-place plate hand, the R-axis movement unit of the pick-and-place plate hand and the pick-and-place plate fork to move along the X-axis.

7. The mask transfer system according to claim 1, wherein The inner mask library unit includes a plurality of inner mask library modules, and each inner mask library template is configured to store multiple mask plates.

8. The mask transfer system according to claim 3, wherein It further includes a support frame, and the support frame includes an upper space and a lower space; The inner mask library unit includes a plurality of inner mask library modules, and the plurality of inner mask library modules are arranged at intervals in the lower space of the support frame along the X-axis direction; The outer mask library unit is installed on the outside of the support frame along the X-axis direction close to the lower space of the support frame; The pick-and-place plate hand unit is arranged in the lower space of the support frame and is arranged opposite to the inner mask library unit along the Y-axis direction; The buffer table unit is installed in the lower space of the support frame. The buffer table unit includes an upper plate buffer table and a lower plate buffer table, and the upper plate buffer table is on the same straight line as the pre-alignment station along the Y-axis direction; The pre-alignment unit is arranged along the Y-axis direction on the outside of the support frame and is arranged close to the buffer table unit; The mask plate exchange hand unit includes a mask plate exchange hand frame, and the mask plate exchange hand unit is installed in the upper space of the support frame through the mask plate exchange hand frame.

9. A method for transferring a photomask, characterized in that, Using the mask transfer system according to any one of claims 1-8 to transfer mask plates, including the following steps: S1: Load the mask plate cassette at the man-machine interface station. The outer mask library unit transfers the mask plate cassette at the man-machine interface station to the first handover station and opens the mask plate cassette; S2: The pick-and-place plate hand unit moves to the first handover station, takes out the mask plate from the opened mask plate cassette, and transfers it to the inner mask library unit. The inner mask library unit performs storage management on the mask plate; S3: The pick-and-place plate hand unit moves to the inner mask library unit, takes out the mask plate, and transfers it to the buffer table unit; S4: The mask plate grasping and positioning mechanism of the mask plate exchange hand unit moves to the buffer table unit and grabs the mask plate; S5: The R-axis motion unit of the changer hand drives the mask gripper positioning mechanism to rotate by a specified angle to meet the requirements of the mask exposure pattern layout design; the mask gripper positioning mechanism drives the mask to move to the mask table handover station, the Z-axis motion unit of the changer hand drives the mask gripper positioning mechanism to descend into the mask table, and the mask gripper positioning mechanism releases the mask and mounts the mask onto the mask table; S6: After exposure is completed, the mask table transports the mask to the mask table handover station, the mask gripper positioning mechanism moves to the mask table handover station, the Z-axis motion unit of the changer hand drives the mask gripper positioning mechanism to descend into the mask table, the mask gripper positioning mechanism grabs the mask in the mask table, and then the Z-axis motion unit of the changer hand drives the mask gripper positioning mechanism to ascend to complete the grabbing of the mask in the mask table; S7: The changer hand unit drives the mask to move and transports the mask to the buffer table unit; S8: The pick-and-place hand unit moves to the buffer table unit, takes out the mask, and transports the mask to the inner magazine unit; S9: The pick-and-place hand unit moves to the inner magazine unit, takes out the mask, and transports the mask to the first handover station; S10: The outer magazine unit transports the mask at the first handover station to the mask cassette at the human-machine interface station.

10. A method for transporting a photomask according to claim 9, characterized in that, Between S4 and S5, there is also included: Pre-alignment operation of the mask: The changer hand unit drives the mask to move to the pre-alignment station, the pre-alignment unit identifies the alignment marks of the mask, obtains the position deviation generated during the mask transportation process, and the changer hand unit adjusts the position of the mask according to the position deviation.

11. A lithographic apparatus, characterized in that, Including the mask transfer system according to any one of claims 1-8.

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