Multi-degree-of-freedom motion device and wafer bearing device

Abstract

The utility model relates to the technical field of semiconductor detection, and relates to a wafer placement table, in particular to a multi-degree-of-freedom movement device and a wafer bearing device. The moving shaft penetrates through the placing seat and can move in the axial direction or / and the circumferential direction based on an external power source; the auxiliary mechanism comprises a first limiting piece connected to the moving shaft in a sleeving mode, and the first limiting piece provides axial movement guide for the moving shaft; the first limiting piece is not in contact with the moving shaft, and the gap is filled with fluid to generate circumferential supporting force and axial guiding on the moving shaft. The air floating sleeve is arranged on the moving shaft, the three limiting columns with the air floating structures and the three axial displacement motors indirectly connected with the moving shaft are arranged, the moving stability of the moving shaft in the axial direction and the circumferential direction can be achieved, and high-precision, high-frequency and high-response vertical movement and rotating movement are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor detection, and relates to a wafer placement table, in particular to a multi-degree-of-freedom motion device and a wafer carrying device. Background Art

[0002] With the development of wafer detection technology, the recognition and positioning accuracy of defects are getting higher and higher. Therefore, it is required that the workpiece stage not only has sufficiently high motion accuracy, but also has real-time compensation functions such as focus tracking. For the defect detection technology of patternless wafers, due to the high rotation speed of the rotating shaft, in the prior art, the technology that can simultaneously achieve high-speed rotation and high-frequency Z-axis movement and compensation is not yet mature. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a multi-degree-of-freedom motion device and a wafer carrying device, which can realize the change of motion state and motion stability during the wafer detection process.

[0004] In a first aspect, a multi-degree-of-freedom motion device is provided, including: a motion axis, passing through a placement seat and capable of moving axially or / and circumferentially based on an external power source; an auxiliary mechanism, including a first limiting member sleeved on the motion axis, the first limiting member providing axial motion guidance for the motion axis; the first limiting member and the motion axis are non-contact, and a fluid is filled in the gap, generating a circumferential supporting force and axial guidance for the motion axis.

[0005] In some specific embodiments, the device further includes a supporting portion disposed on the placement seat and connected to the first limiting member, the supporting portion being used to provide a circumferential supporting force to the first limiting member to keep the positional relationship between the first limiting member and the motion axis stable.

[0006] In some specific embodiments, the first limiting member is an air bearing sleeve, the fluid is compressed gas, and compressed air is introduced into the gap between the air bearing sleeve and the motion axis to form an air film, so that the first limiting member and the motion axis are non-contact.

[0007] In some specific embodiments, the supporting portion includes at least two limiting columns disposed on the placement seat, at least two of the limiting columns being uniformly arranged around the motion axis; at least two of the limiting columns are connected to the first limiting member through a connecting member.

[0008] In some specific embodiments, the number of the limiting columns is three.

[0009] In some specific embodiments, the external power source includes: a first power source, a rotating motor disposed at the tail end of the motion axis, providing circumferential motion power for the motion axis; a second power source, capable of outputting power axially, providing axial motion power for the motion axis.

[0010] In some specific embodiments, the second power source includes an axial displacement motor disposed on the placement seat and is connected to the side of the rotary motor through a fixing member to drive the rotary motor to move axially, thereby driving the moving shaft to move axially.

[0011] In some specific embodiments, the number of the axial displacement motors is at least two and they are uniformly arranged around the moving shaft.

[0012] In some specific embodiments, the axial displacement motors and the limiting columns are uniformly and staggeredly distributed.

[0013] In some specific embodiments, the limiting column includes a shaft body and a shaft sleeve, and the shaft sleeve can axially move along the shaft body. The shaft body is arranged parallel to the moving shaft, and the shaft sleeve is connected to the rotary motor.

[0014] In some specific embodiments, the limiting column includes an air floating shaft and an air floating shaft sleeve sleeved on the air floating shaft. One end of the air floating shaft is fixedly connected to the placement seat, and the other end is connected to the connecting member. There is a gap between the air floating shaft sleeve and the air floating shaft, and compressed air is introduced into the gap to form an air film so that the air floating shaft sleeve and the air floating shaft do not contact each other. The air floating shaft sleeve is connected to the rotary motor.

[0015] In some specific embodiments, the connecting member is an annular structure sleeved on the outside of the first limiting member, provided with a plurality of connecting positions, and the plurality of connecting positions are respectively connected to the tops of at least two of the air floating shafts.

[0016] In some specific embodiments, the air floating shaft sleeve is connected to the rotary motor through a decoupling member. One end of the decoupling member is disposed at a position relative to the limiting column outside the rotary motor, and the other end is connected to the limiting column.

[0017] In some specific embodiments, the decoupling member includes a base disposed outside the rotary motor and a connecting piece extending from the base towards the air floating shaft sleeve, and the connecting piece is connected to the air floating shaft sleeve.

[0018] In some specific embodiments, the rigidity of the connecting piece in the horizontal directions X, Y, and Rz is greater than that in the directions Rx, Ry, and Z.

[0019] In some specific embodiments, the rotary motor includes a housing and a power member disposed in the housing. The connecting piece is connected to the housing.

[0020] In some specific embodiments, it further includes a balancing member passing through the fixing member and connected to the placement seat, and the balancing member is designed to reduce the axial load.

[0021] In some specific embodiments, the balancing member is a spring.

[0022] In some specific embodiments, an adjusting member is provided at one end of the balancing member that is not connected to the placement seat, for adjusting the compression amount of the spring.

[0023] In a second aspect, a wafer carrier device is provided, including the multi-degree-of-freedom motion device described in any one of the above, and a carrier table is provided at the upper end of the motion axis, and the carrier table can move synchronously along the axial direction and the circumferential direction based on the motion axis.

[0024] The embodiments of the present invention bring the following beneficial effects:

[0025] The embodiments of the present invention provide a multi-degree-of-freedom motion device and a wafer carrier device. By providing an air-floating structure on the motion axis, axial guidance and circumferential support of the motion axis are achieved. The air-floating structure can achieve no friction during the movement of the motion axis, and can achieve high-precision, high-frequency, and high-response control in the vertical direction and the rotational direction.

[0026] Other features and advantages of the present disclosure will be described in the following description, or, some features and advantages can be inferred from the description or determined without doubt, or can be learned by implementing the above technologies of the present disclosure.

[0027] To make the above objects, features, and advantages of the present disclosure more obvious and understandable, the following specific preferred embodiments are given below, and in conjunction with the accompanying drawings, detailed descriptions are as follows. Description of the Drawings

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1 Schematic structural diagram of a multi-degree-of-freedom motion device provided by an embodiment of the present invention;

[0030] Figure 2 Schematic structural diagram of the limit post provided by an embodiment of the present invention;

[0031] Figure 3 Another schematic structural diagram of a multi-degree-of-freedom motion device provided by an embodiment of the present invention;

[0032] Figure 4 Wafer carrier device provided by an embodiment of the present invention.

[0033] Icons: 10 - Multi - degree - of - freedom motion device; 20 - Carrying platform; 30 - Wafer carrying device;

[0034] 11 - Motion axis; 12 - Auxiliary mechanism; 13 - First power source; 14 - Second power source; 15 - Support part; 16 - Placement seat;

[0035] 121 - First limiting part;

[0036] 141 - Axial displacement motor; 142 - Fixing part; 143 - Balancing part; 144 - Adjusting component;

[0037] 151 - Limiting column; 152 - Connecting part; 153 - Air - floating axis; 154 - Air - floating bushing; 155 - Decoupling part; 156 - Base; 157 - Connecting piece; 158 - Wrapping space. Detailed implementation mode

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0039] The wafer positioning device provided in the embodiments of the present application is applied to the semiconductor front - end detection scenario, specifically for the scenario of detecting wafers. In this scenario, the detection method is to scan the wafer surface along a specific path by laser, obtain the optical information of each position on the wafer surface, and determine whether there are defects on the wafer surface based on this optical information. Among them, when the laser scans, the wafer needs to have two motion states.

[0040] Specifically, the first state is the rotation state, that is, the wafer needs to rotate at a set speed during scanning, and the second state is that during the scanning process, it needs to be compensated along the z - axis to keep the wafer at a specific height position. Therefore, during the wafer detection process, rotational motion and axial motion control of the wafer are required. Moreover, the above two motion states can be carried out synchronously.

[0041] In this embodiment, the above two motion states can be carried out synchronously, but it does not exclude that the above two motion states are carried out step by step. It includes moving alone in the first state and moving alone in the second state.

[0042] When implementing the above two motion states for the wafer, a rotational circumferential disturbance will be generated for the first state, and an axial disturbance will be generated for the second state. The above two motion disturbances will affect the wobbling of the carried wafer. Since wafer detection is based on laser irradiation and surface scanning is performed along a corresponding path, the generated wobbling will cause problems such as damage to the scanning path and poor stability of the incident laser and reflected laser beams.

[0043] Therefore, when the motion is in progress, it is necessary to eliminate the above disturbances and maintain the stability of the wafer motion.

[0044] Based on the above background, this embodiment provides a multi-degree-of-freedom motion device 10 for implementing the above two motion states of the wafer, and reducing the disturbances caused by mechanical motion during the motion process to achieve the maintenance of wafer stability.

[0045] Specifically, for this device, refer to Figure 1 , including a placement seat and a motion shaft 11 passing through the placement seat and connected to an external power source.

[0046] Among them, the motion shaft is a motion execution mechanism. The rotation of the wafer and the axial motion of the wafer are both realized based on this mechanism. Although the motion shaft is not directly connected to the wafer, the motion shaft drives the wafer carrier component to achieve the rotational motion and axial motion of the wafer.

[0047] Specifically, for the realization of the motion of the motion shaft, it is realized by configuring an external power source. This external power source should be able to realize the axial and circumferential motions of the motion shaft. This external power source includes a first power source 13 and a second power source 14. The first power source is used to make the motion shaft perform circumferential motion, that is, rotational motion, and the second power source is used for the motion shaft to perform axial motion.

[0048] Among them, the specific structure of the first power source is a rotary motor arranged at the tail end of the motion shaft. The rotary motor drives the motion shaft to rotate by outputting rotational power. The second power source will be described in detail later. First, it is necessary to elaborate on the components for realizing the maintenance of wafer stability.

[0049] Specifically, the control of the stability of the wafer is based on the control of the stability of the motion shaft. Therefore, in this embodiment, it is necessary to configure an auxiliary mechanism 12 for the motion shaft that can cancel the disturbances generated during rotational and axial motions.

[0050] The auxiliary mechanism includes a first limiting member 121 sleeved on the moving shaft. This limiting member provides axial movement guidance for the moving shaft through the sleeved structure, that is, the moving shaft moves axially within the hollow space of this component. In order to achieve guidance, there should be no gap between the first limiting member and the moving shaft, because the generation of a gap will cause the circumferential movement of the moving shaft to be unstable. However, it should be noted that if the moving shaft and the first limiting member are completely fitted, mechanical friction will be generated between the two during high-speed movement. Friction can not only cause damage to the components, but also lead to problems such as movement instability due to the gap generated by the damage.

[0051] Therefore, in order to avoid the above technical problems, there is a gap between the first limiting member and the moving shaft, that is, the two have a non-contact connection relationship, and the circumferential movement of the moving shaft is stabilized by filling a fluid medium in the gap between the two, and the frictional force caused by the fluid medium on the moving shaft can be ignored from an engineering perspective.

[0052] Specifically, in this embodiment, the gap between the first limiting member and the moving shaft is filled with a fluid, and the fluid fills this gap, thereby generating a supporting force for the circumferential direction of the moving shaft. And because the first limiting member and the moving shaft are non-contact, the damage to the moving shaft caused by metal-to-metal friction is reduced.

[0053] Among them, this fluid includes but is not limited to gases, liquids, and other fluid forms. However, in this embodiment, a gas is preferably used as the filling medium for the gap, and the gas is a compressed gas, and an air film is formed by the compressed gas.

[0054] Among them, in order to increase the contact area of the filled compressed gas, the first limiting member in this embodiment adopts a sleeve structure. This sleeve structure can be defined as an air bearing sleeve based on the working principle of introducing compressed gas. The air bearing sleeve is sleeved on the moving shaft and filled with compressed gas, and an air film is formed by the compressed gas, so that the air bearing sleeve and the moving shaft are non-contact. Also, because of the acting force generated by the compressed gas, the position stability of the moving shaft during rotation and axial movement can be maintained, and the wear of the moving shaft during movement is reduced, so that the position relationship of the moving shaft is kept stable, thereby ensuring the stability of the movement process of the driven wafer.

[0055] Among them, an air inlet channel is also provided for the air bearing sleeve, and the air inlet channel is connected to an external gas generating device to realize the conduction of the compressed gas in the air bearing sleeve.

[0056] The air bearing sleeve can apply a force to the moving shaft through a non-contact fluid medium to maintain the stability of the moving shaft. However, the air bearing sleeve will also generate disturbances due to high-speed rotation. Although this disturbance is small, in order to further maintain the stability of the air bearing sleeve, a support portion 15 is provided in this embodiment to provide circumferential support force and axial force to the first limiting member, that is, the air bearing sleeve, and further ensure the stability of the moving shaft by ensuring the stability of the first limiting member.

[0057] Specifically, this support portion includes a plurality of limiting columns 151 provided on the placement seat. These limiting columns are evenly arranged around the moving shaft, and the limiting columns are connected to the side end of the air bearing sleeve through connecting members 152.

[0058] Among them, since this limiting column is fixedly connected to the placement seat, the relative position of the limiting column in the overall device will not change. Because this component is connected to the air bearing sleeve, the relative position of the connected air bearing sleeve can be stabilized under the condition that the relative position of the limiting column remains unchanged, thereby ensuring the stable movement of the moving shaft.

[0059] In this embodiment, the number of limiting columns is at least two, and the two should be evenly arranged along the moving shaft. Specifically, when the number of limiting columns is two, the included angle between the two is 180°.

[0060] In order to further ensure the optimal effect of the limiting column, in this embodiment, it is preferred to use three limiting columns as the optimal implementation method. The three limiting columns can ensure that there is a support force at any angle in the circumferential direction, thereby ensuring the stability of the air bearing sleeve and the moving shaft more completely.

[0061] Moreover, for the connecting member, in order to maximize the contact area with the air bearing sleeve, this connecting member is an annular structure sleeved on the outside of the air bearing sleeve. A plurality of connecting positions are provided on this connecting member, and these connecting positions are respectively connected to the top ends of the limiting columns. Since the number of limiting columns preferably used in this embodiment is three, there are also three connecting positions provided on the connecting member. Through the connection between this connecting member and the limiting column, the guiding and supporting of the air bearing sleeve are realized.

[0062] Please continue to refer to Figure 1 , the second power source in this embodiment is the axial displacement motor 141, and it drives the moving shaft to perform axial movement through its movement in the axial direction.

[0063] However, it should be noted that since the moving shaft also has circumferential rotational movement, if the axial displacement motor is directly connected to the moving shaft, the axial displacement motor will be driven to perform synchronous movement, and this structure will inevitably cause the complexity of the overall device structure and the control difficulty of the movement stability.

[0064] Therefore, in this embodiment, the axial displacement motor is not directly connected to the moving shaft. It is fixedly placed on the placement seat and directly connected to the rotating motor through the fixing member 142, thereby forming an indirect connection relationship with the moving shaft. The axial displacement motor drives the rotating motor to move axially, thereby driving the moving shaft to move indirectly along the axis, avoiding the problem of the complexity of motion control caused by the direct connection relationship.

[0065] Moreover, for the rotating motor in this embodiment, like all motors in the prior art, it includes at least one housing. A power member is provided in the housing. The power member is a component that performs specific motions. When the rotating motor moves, the relative position of its own housing does not change.

[0066] Therefore, the axial displacement motor in this embodiment should be connected to the housing to ensure that its position does not change according to the movement of the rotating motor.

[0067] Specifically, the axial displacement motor in this embodiment is preferably a voice coil motor.

[0068] Similarly, the number of axial displacement motors in this embodiment is at least two, and they are arranged in a uniform arrangement. Preferably, in this embodiment, the optimal arrangement of three is adopted, and the three axial displacement motors are arranged crosswise with the three limit posts, making the spatial design and layout more reasonable.

[0069] As can be seen from the above, in the embodiment of the present application, by setting the axial displacement motor to be connected to the rotating motor, the axial movement of the moving shaft is realized by driving the rotating motor to move axially.

[0070] However, it should be noted that by setting the first limiting member and the supporting portion, it can be ensured that the moving shaft has a supporting force in the circumferential direction and a guiding result in the axial direction, thereby ensuring the stability of the moving shaft during the movement process. However, for the rotating motor during axial movement, the above structure cannot ensure the same stability during the movement process.

[0071] To solve this technical problem, the embodiment of the present application optimizes the structure of the limit post so that it can realize the guiding function for the rotating motor while ensuring the circumferential supporting force provided by the first limiting member.

[0072] Specifically, regarding this limit post, it includes at least one fixed and immovable shaft body. Both ends of this shaft body are fixed respectively by connecting with a connecting piece and a placement seat. And a sleeve body sleeved outside the shaft body. The shaft body has the same axial direction as the rotating motor. The sleeve body can move along the axial direction of the shaft body. And by setting an intermediate medium between the sleeve body and the shaft body, the moving path of the sleeve body will not deviate in the circumferential direction, and this moving path is a single path. The sleeve body is connected with the rotating motor through a connecting piece. When the rotating motor moves axially, through the limitation of the single moving path of the sleeve body, the axial movement of the rotating motor has a limiting effect, thereby realizing the guiding function of the rotating motor.

[0073] In this embodiment, in order to reduce the wear caused by the relative displacement between the sleeve body and the shaft body, the limit post is implemented by adopting the same air-floating structure as the first limiting piece.

[0074] Please refer to Figure 2 , regarding this limit post, it includes an air-floating shaft 153 and an air-floating shaft sleeve 154 sleeved on the air-floating shaft. And compressed gas is introduced into the gap between the air-floating shaft and the air-floating shaft sleeve to form an air film through the compressed gas.

[0075] One end of the air-floating shaft is fixedly arranged on the placement seat, and the other end is connected with the connecting piece. The overall axial direction is parallel to that of the rotating motor. The air-floating sleeve is connected with the rotating motor. When the rotating motor moves axially, the air-floating sleeve makes a synchronous connection. Due to the relationship of the air-floating shaft, the air-floating sleeve has a stable moving path, and further ensures that the axial movement of the rotating motor is in a stable state.

[0076] In this embodiment, through the optimization of the limit post, the guiding of the moving shaft in the axial direction and the stability of the movement in the axial and circumferential directions can be realized.

[0077] It should be noted that during the rotation process of the rotating motor, circumferential disturbances will be generated. A small part of the disturbances is conducted to the moving shaft and can be offset by the air-floating sleeve and the limit post. However, most of the disturbances will be conducted to the structures connected to it, thereby reducing the stability of the overall operation of the device.

[0078] In order to eliminate the problems caused by this circumferential disturbance, it is necessary to offset the disturbance. However, because the components connected to the rotating motor are all fixed rigid components, it is very difficult to design for disturbance offset. Therefore, in this embodiment, in order to eliminate the internal stress problem in the system caused by the disturbance of the rotating motor, a decoupling piece 155 is arranged between the limit post and the rotating motor. One end of the decoupling piece is arranged at the position of the air-floating shaft sleeve of the housing relative to the limit post, and the other end is directly connected with the air-floating shaft sleeve.

[0079] Specifically, the decoupling component includes a base 156 disposed outside the rotating motor and a connecting piece 157 extending from the base towards the air bearing sleeve, and the connecting piece is directly connected to the air bearing sleeve.

[0080] Among them, the connecting piece is preferably a reed piece. The connecting piece has strong rigidity in the horizontal directions Y, Y and the Rz direction to withstand the reaction force of the rotating motor and reduce the influence of the disturbance generated by the rotating motor on the overall device.

[0081] Moreover, the connecting piece has weak rigidity in the Rx, Ry and Z directions, and can also eliminate the influence of non-parallel installation among the three air bearing sleeve components, thereby reducing the internal stress of the system.

[0082] In this embodiment, since the air bearing sleeve has a circular cross-section, in order to ensure the tightness of the connection relationship between the connecting piece and the air bearing sleeve and increase the connection base area. The connecting piece in this embodiment is unfolded along an arc at the connection with the air bearing sleeve to form a wrapping space 158, and this wrapping space is attached to the side of the air bearing sleeve and connected through mechanical parts, realizing the full connection between the air bearing sleeve and the connecting piece.

[0083] From the above structure, it can be seen that in the embodiment of the present application, by configuring an air bearing sleeve and a limit post, the movement stability of the moving shaft is ensured through the air bearing structure.

[0084] Regarding the rotational movement and axial movement in the embodiment of the present application as high-frequency movements, their rotational movement and axial movement have large movement loads. In order to achieve high responsiveness of the axial movement, it is necessary to optimize the axial displacement motor structure in this embodiment.

[0085] Specifically, please refer to Figure 3 , a balancing member 143 is provided between the fixing member and the placement seat for this axial displacement motor. Among them, this balancing member is designed to reduce the axial load.

[0086] Among them, this balancing member can be designed as a compressible elastic member, and the load is eliminated through this elastic balancing member.

[0087] Specifically, this elastic member can be a spring, and an adjusting member 144 is further provided at the top end of the elastic member, that is, the end not connected to the placement seat, for adjusting the compression amount of the balancing member, that is, the elasticity of the balancing member, so that the sum of the elastic forces of the three balancing members is equivalent to the movement load in the vertical direction. Through this structure, the load of the axial displacement motor can be greatly reduced, and the response characteristics of the moving shaft can be improved.

[0088] In summary, for the multi-degree-of-freedom motion device provided in this embodiment, the optimal implementation means is to set an air bearing sleeve on the motion axis. By setting three limit posts with air bearing structures and three axial displacement motors indirectly connected to the motion axis, the motion stability of the motion axis in the axial and circumferential directions can be achieved, and high-precision, high-frequency, and high-response vertical and rotational motions can be realized.

[0089] Please refer to Figure 4 , based on the above motion device, a wafer carrier device 30 is further provided. On the upper end of the motion axis in the multi-degree-of-freedom motion device shown in Figure 3 , a carrier stage 20 is provided. The carrier stage is used to place the wafer to be detected and can move synchronously along the axial and circumferential directions based on the motion axis, so as to realize the optical scanning detection of the wafer.

[0090] Among them, the "wafer" in this embodiment generally refers to a substrate formed of semiconductor or non-semiconductor materials. Examples include (but are not limited to) single crystal silicon, gallium arsenide, gallium nitride, and indium phosphide. Such substrates can usually be found and / or processed in semiconductor manufacturing facilities. In some cases, the wafer may only include the substrate (i.e., a bare die). Alternatively, the wafer may include one or more different material layers formed on the substrate. One or more layers formed on the wafer may be "patterned" or "unpatterned". For example, the wafer may include multiple bare dies with repeatable pattern features.

[0091] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", 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, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0092] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-degree-of-freedom motion device, characterized in that: include: A motion shaft is provided through the placement seat and can move in the axial direction or / and the circumferential direction based on an external power source; The auxiliary mechanism includes a first limit member sleeved on the moving shaft, the first limit member provides axial movement guidance for the moving shaft; there is non-contact between the first limit member and the moving shaft, and the gap is filled with fluid, which generates circumferential support force and axial guidance for the moving shaft.

2. The multi-degree-of-freedom motion device according to claim 1, characterized in that: The device also includes a support portion disposed on the placement seat and connected to the first position-limiting member, wherein the support portion is used to provide a circumferential support force to the first position-limiting member so that the positional relationship between the first position-limiting member and the motion axis remains stable.

3. The multi-degree-of-freedom motion device according to claim 1, characterized in that: The first position-limiting member is an air-floating sleeve, the fluid is compressed gas, and compressed air is introduced into the gap between the air-floating sleeve and the moving shaft to form an air film, so that the first position-limiting member is non-contact with the moving shaft.

4. The multi-degree-of-freedom motion device according to claim 2, characterized in that: The support portion includes at least two limiting columns arranged on the placement seat, and the at least two limiting columns are evenly arranged around the motion axis; and the at least two limiting columns are connected to the first limiting member through a connecting member.

5. The multi-degree-of-freedom motion device according to claim 4, characterized in that: The number of the limiting columns is three.

6. The multi-degree-of-freedom motion device according to claim 4, characterized in that: The external power source comprises: A first power source, a rotary motor disposed at the rear end of the motion shaft, providing circumferential motion power for the motion shaft; The second power source can output power in the axial direction to provide axial motion power for the motion shaft.

7. The multi-degree-of-freedom motion device according to claim 6, characterized in that: The second power source includes an axial displacement motor disposed on a placement seat and connected to a side surface of the rotating motor through a fixing member, so as to drive the rotating motor to move axially, thereby driving the moving shaft to move axially.

8. The multi-degree-of-freedom motion device according to claim 7, characterized in that: The number of the axial displacement motors is at least two and they are evenly arranged around the motion axis.

9. The multi-degree-of-freedom motion device according to claim 8, characterized in that: The axial displacement motors and the limiting columns are evenly and staggeredly distributed.

10. The multi-degree-of-freedom motion device according to claim 6, characterized in that: The limiting column includes a shaft body and a shaft sleeve, and the shaft sleeve can move axially along the shaft body. The shaft body is arranged parallel to the moving shaft, and the shaft sleeve is connected to the rotating motor.

11. The multi-degree-of-freedom motion device according to claim 10, characterized in that: The limiting column includes an air-floating shaft and an air-floating shaft sleeve sleeved on the air-floating shaft, one end of the air-floating shaft is fixedly connected to the placement seat, and the other end is connected to the connecting piece; there is a gap between the air-floating shaft sleeve and the air-floating shaft, and compressed air is introduced into the gap to form an air film, so that the air-floating shaft sleeve and the air-floating shaft are not in contact; the air-floating shaft sleeve is connected to a rotating motor.

12. The multi-degree-of-freedom motion device according to claim 11, characterized in that: The connecting member is an annular structure sleeved on the outside of the first limiting member, and is provided with a plurality of connecting positions, and the plurality of connecting positions are respectively connected to the top ends of at least two of the air floating shafts.

13. The multi-degree-of-freedom motion device according to claim 11, characterized in that: The air-floating sleeve is connected to the rotating motor via a decoupling member, one end of the decoupling member is arranged at a position outside the rotating motor relative to the limiting column, and the other end is connected to the limiting column.

14. The multi-degree-of-freedom motion device according to claim 13, characterized in that: The decoupling member includes a base arranged on the outside of the rotating motor, and a connecting piece extending along the base toward the air-floating sleeve, wherein the connecting piece is connected to the air-floating sleeve.

15. The multi-degree-of-freedom motion device according to claim 14, characterized in that: The rigidity of the connecting piece in the horizontal directions X, Y and Rz is greater than the rigidity in the directions Rx, Ry and Z.

16. The multi-degree-of-freedom motion device according to claim 14, characterized in that: The rotating electrical machine comprises a housing and a power member arranged in the housing; the connecting piece is connected to the housing.

17. The multi-degree-of-freedom motion device according to claim 10, characterized in that: It also includes a balancing piece that penetrates the fixing piece and is connected to the placement seat, and the balancing piece is designed to reduce the axial load.

18. The multi-degree-of-freedom motion device according to claim 17, characterized in that: The balance member is a spring.

19. The multi-degree-of-freedom motion device according to claim 18, characterized in that: An adjusting component is arranged at one end of the balancing member which is not connected to the placing seat, and is used for adjusting the compression amount of the spring.

20. A wafer carrying device, characterized in that: It comprises the multi-degree-of-freedom motion device as described in any one of claims 1 to 19, and a bearing platform is arranged at the upper end of the motion axis, and the bearing platform can move synchronously in the axial direction and the circumferential direction based on the motion axis.

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