Weak coupling two-dimensional precision motion platform driven by bias

Abstract

The application relates to the technical field of precise motion platforms, in particular to a weak-coupling two-dimensional precise motion platform driven by biasing, which comprises a fixed base and a two-dimensional motion platform, the two-dimensional motion platform comprises an intermediate platform, a platform main body, piezoelectric driving units, a biasing flexible amplification unit and sensors, the intermediate platform is located in the platform main body, two piezoelectric driving units are respectively arranged in two accommodating grooves which are orthogonally arranged near the intermediate platform on the platform main body, the output ends of the two piezoelectric driving units are matched with the biasing flexible amplification unit, two sensors are respectively arranged on the adjacent two side surfaces of the intermediate platform, a first L-shaped groove is arranged at the vertex of the intermediate platform, a second L-shaped groove is arranged at the corresponding position of the platform main body, and the two form a guiding decoupling unit. Through the biasing flexible amplification unit and the guiding decoupling unit, parasitic motion is effectively inhibited, and the two-dimensional motion purity, the repeat positioning accuracy and the overall stability of the platform are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of precision motion platform technology, and particularly relates to a bias-driven, weakly coupled two-dimensional precision motion platform. Background Technology

[0002] As semiconductor manufacturing processes continue to evolve towards nanometer-level nodes, extremely stringent requirements are placed on the performance of precision motion platforms in core processes such as wafer alignment, photolithography, defect detection, probe testing, and advanced packaging. These high-end equipment not only require motion platforms to possess sub-micron or even nanometer-level displacement resolution and high repeatability within a small travel range, but also demand extremely high attitude stability and linearity under high-speed dynamic response. Especially in high-precision photolithography and inspection scenarios, any minute parasitic displacement, angular sway, or vibration error can lead to decreased pattern overlay accuracy, deteriorated imaging quality, or probe contact failure, directly impacting chip yield and manufacturing costs.

[0003] Currently, to meet the aforementioned ultra-precision positioning requirements, flexible hinge mechanisms driven by piezoelectric actuators are widely used in semiconductor equipment. Compared to traditional rolling guides or lead screw drives, piezoelectric flexible platforms have become the mainstream choice in the field of semiconductor precision manufacturing due to their significant advantages such as frictionless, backlash-free, wear-free operation, high response frequency, and ease of achieving micro-nano-level control. However, although existing two-dimensional piezoelectric precision motion platforms can theoretically achieve multi-degree-of-freedom micro-displacement output, significant technical bottlenecks still exist in their structural design and motion performance in practical high-precision semiconductor manufacturing applications, mainly in the following three aspects: 1. Attitude instability caused by additional torque during flexible transmission. Existing flexible motion platforms typically utilize the elastic deformation of thin beams or flexible hinges to transmit displacement. However, in most existing structures, the design of flexible hinges often focuses on achieving displacement transmission and amplification, neglecting the mechanical coupling characteristics during deformation. When a piezoelectric actuator drives the flexible hinge to undergo elastic deformation, additional torque is easily generated at the flexible node due to structural non-ideal symmetry or offset of the force center. This additional torque is directly transmitted to the intermediate moving platform, causing the moving platform to produce unexpected parasitic rotation or slight yaw while performing the target translational motion. In semiconductor processing, this attitude instability directly disrupts the depth of focus range of processing or inspection, severely affecting process accuracy.

[0004] 2. Motion coupling between multiple degrees of freedom leads to difficulties in independent control. Existing two-dimensional platforms mostly use orthogonally arranged dual-drive branches or parallel structures to achieve planar motion. However, due to the lack of an effective mechanical decoupling mechanism, strong motion coupling often exists between drive branches in different directions. Specifically, when a piezoelectric actuator in one direction operates, the driving force or deformation it generates is transmitted to another direction through a common structure or flexible hinge, resulting in parasitic displacement in the non-drive direction (i.e., cross-coupling error). This degree-of-freedom coupling phenomenon makes the input-output relationship of the platform nonlinear, greatly increasing the modeling difficulty and compensation cost of the control system, making it difficult to meet the control requirements of semiconductor devices for high dynamics and high decoupling performance.

[0005] 3. The overall structure struggles to balance compactness, guidance, and high rigidity. Existing two-dimensional micro-motion platforms are mainly divided into two categories: serial stacked type and parallel type. Although the serial structure is simple to control, it has large cumulative errors and excessive vertical dimensions, which is not conducive to the miniaturization and integration of equipment; while the parallel structure, although compact, often faces problems such as small working space and inconsistent stiffness of each branch. In addition, existing platforms have shortcomings in guidance constraint design, making it difficult to simultaneously achieve strong constraints on non-target degrees of freedom and compliant actuation of target degrees of freedom within a limited space. Summary of the Invention

[0006] In view of this, the present invention aims to provide a bias-driven, weakly coupled two-dimensional precision motion platform to solve the problems of attitude instability, motion coupling, and structural redundancy caused by the flexible structure defects of existing semiconductor two-dimensional piezoelectric motion platforms. It provides a precision motion solution that integrates high stability, low coupling, and miniaturization, improves the purity of two-dimensional motion, repeatability, and overall stability of the platform, thereby meeting the needs of high-precision micro-motion platforms in semiconductor manufacturing scenarios such as wafer alignment, exposure positioning, defect detection, probe testing, and advanced packaging.

[0007] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A bias-driven, weakly coupled two-dimensional precision motion platform includes a fixed base and a two-dimensional motion platform, wherein the two-dimensional motion platform is disposed on the top surface of the fixed base; The two-dimensional motion platform includes an intermediate platform, a platform body, piezoelectric drive units, a biased flexible amplification unit, and sensors. The platform body is mounted on the top surface of a fixed base. The intermediate platform is located within the platform body and is integrally formed with the platform body. Two receiving slots are formed near one vertex of the intermediate platform on the platform body. The two receiving slots are orthogonally arranged. Two piezoelectric drive units are respectively disposed in the receiving slots. The output end of each piezoelectric drive unit is adapted to one end of the corresponding biased flexible amplification unit, and the other end of the biased flexible amplification unit is connected to the intermediate platform. Two sensors are respectively disposed on two adjacent sides of the intermediate platform. Each sensor is located on the same side of the intermediate platform as the output end of the corresponding piezoelectric drive unit. The piezoelectric drive unit drives the corresponding biased flexible amplification unit to move. When the sensor detects displacement of the intermediate platform, the external controller receives the displacement and converts it into a drive command, which is then sent to the corresponding piezoelectric drive unit. The piezoelectric drive unit operates and drives the corresponding biased flexible amplification unit to apply an actuation displacement opposite to the direction of movement to the intermediate platform, thereby suppressing the vibration of the intermediate platform and maintaining its steady state. The biased flexible amplification unit includes a biased flexible body, an arc-shaped anchoring part, a driven part, and a biased flexible thin beam. One end of the arc-shaped anchoring part, one end of the driven part, and one end of the biased flexible thin beam are all connected to the side of the biased flexible body near the intermediate platform. The other end of the arc-shaped anchoring part is connected to the platform body, and the other end of the biased flexible thin beam is connected to the intermediate platform. The driven part is located between the arc-shaped anchoring part and the biased flexible thin beam. The other end of the driven part has a driving contact surface, which abuts against the output end of the corresponding piezoelectric driving unit to receive the driving force transmitted along the axial direction of the driven part. When the piezoelectric driving unit is working, it pushes the biased flexible body to translate through the driven part to suppress the vibration of the intermediate platform.

[0008] Each of the apexes of the intermediate platform is provided with a first L-shaped groove, and a second L-shaped groove is provided on the platform body near the first L-shaped groove. The corresponding first L-shaped groove and second L-shaped groove are arranged in parallel, and the corresponding first L-shaped groove and second L-shaped groove form a guide decoupling unit.

[0009] Furthermore, the distance between the offset flexible thin beam and the corresponding centerline on the intermediate platform is the offset dimension, and the formula for calculating the offset dimension is: ; In the formula, For offset dimensions, To transmit the original parasitic torque to the intermediate platform, The equivalent stiffness of the biased flexible thin beam. This is the equivalent minute rotation angle corresponding to the biased flexible amplification unit during operation.

[0010] Furthermore, the width of both the first L-shaped groove and the second L-shaped groove is 0.2 mm.

[0011] Furthermore, the piezoelectric drive unit includes a piezoelectric actuator and a preload pad. The piezoelectric actuator is embedded in the receiving groove, and the output end of the piezoelectric actuator is bonded to the preload pad. The preload pad is in contact with the driven part, and the piezoelectric actuator pushes the driven part to move through the preload pad.

[0012] Furthermore, the end of the preload gasket that contacts the driven part has a spherical structure, which improves the self-adaptive ability of the preload gasket in contact with the driven part.

[0013] Furthermore, the platform body includes a first L-shaped body and a second L-shaped body. The horizontal and vertical parts of the first L-shaped body are of equal length, and the horizontal and vertical parts of the second L-shaped body are of equal length. The horizontal part of the first L-shaped body is longer than the horizontal part of the second L-shaped body. The first L-shaped body and the second L-shaped body are respectively fixed on two areas diagonally distributed on the top surface of the fixed base. The other ends of the two arc anchoring parts are respectively connected to the two ends of the first L-shaped body. Two offset flexible thin beams are respectively set close to the two ends of the second L-shaped body. The first L-shaped body, the second L-shaped body and the two offset flexible bodies are arranged around the middle platform. The second L-shaped groove is opened on the first L-shaped body and the second L-shaped body. When the piezoelectric actuator outputs axial displacement, the driven part transmits the displacement to the biased flexible thin beam. One end of the biased flexible body is connected and fixed to the first L-shaped body through the arc anchoring part. The driven part transmits the axial displacement to the biased flexible thin beam through the biased flexible body. The biased flexible thin beam undergoes expansion and contraction deformation and moves in a translational motion after being subjected to force as a whole with the biased flexible body, converting the small axial displacement output by the piezoelectric actuator into a displacement that restricts the movement of the intermediate platform.

[0014] Furthermore, the end of the first L-shaped main body has a limiting part, which is perpendicular to the end of the first L-shaped main body and is located between the corresponding biased flexible main body and the first L-shaped main body.

[0015] Furthermore, the four sides of the intermediate platform are recessed inward to form a first groove. The first L-shaped groove is opened on the intermediate platform near the first L-shaped body, the second L-shaped body and the limiting part. The second L-shaped groove is opened on the first L-shaped body, the second L-shaped body and the limiting part near the intermediate platform.

[0016] Furthermore, the two-dimensional motion platform also includes a sensor mounting base. One end of the sensor is located near the bottom of the first groove, and the other end of the sensor is mounted on the sensor mounting base. The bottom of the sensor mounting base is mounted on a fixed base. The sensor is used to detect, provide feedback, or measure displacement signals in the corresponding direction, so as to monitor the motion state of the intermediate platform in real time.

[0017] Furthermore, the top surface of the fixed base is recessed inward near the offset flexible body to form a second groove, which extends to the side of the fixed base. A square through slot is provided on the top surface of the fixed base, corresponding to the position of the intermediate platform. A third groove is formed by recessing inward on the side wall of the square through slot near the sensor. The bottom of the sensor mounting base is installed on the bottom of the third groove, which shortens the detection distance between the sensor and the intermediate platform, enabling the sensor to more accurately sense the vibration signal and displacement change of the intermediate platform.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The present invention effectively suppresses non-target rotation, sway and parasitic displacement of the intermediate platform in the two-dimensional motion process through the synergistic effect of the bias flexible amplification unit and the guide decoupling unit, and significantly improves the motion purity of the platform; the intermediate platform has extremely high repeatability and output stability, and can be competent for semiconductor manufacturing processes with extremely high consistency requirements such as wafer alignment and probe testing.

[0019] (2) The present invention achieves miniaturization and compactness while ensuring high precision, low coupling and high stability through piezoelectric drive unit, bias flexible amplification unit and guide decoupling unit.

[0020] (3) The present invention sets up a guide decoupling unit at the four corners of the intermediate platform, which can effectively constrain the non-target degrees of freedom and physically block the side effects (cross coupling) of the drive in one direction on the other direction; significantly improves the independence of the two orthogonal directions of motion, making the input-output relationship of the intermediate platform more linear and clear, greatly reducing the complexity of the control system modeling and error compensation, and improving the dynamic response performance and positioning accuracy of the platform. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the bias-driven, weakly coupled two-dimensional precision motion platform described in an embodiment of the present invention; Figure 2 for Figure 1 Top view; Figure 3 for Figure 2 A schematic diagram of the structure without the piezoelectric drive unit; Figure 4 for Figure 3 A schematic diagram of the structure of the sensor mounting base; Figure 5 for Figure 2 Schematic diagram of the structure of the fixed base; Figure 6 The diagram shows the usage status of the bias-driven, weakly coupled two-dimensional precision motion platform described in the embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Fixed base; 2. Two-dimensional motion platform; 11. Second groove; 12. Square through groove; 13. Third groove; 20. Intermediate platform; 21. Platform body; 22. Piezoelectric drive unit; 23. Biased flexible amplification unit; 24. Sensor; 25. Sensor mounting base; 26. Guiding decoupling unit; 27. First L-shaped groove; 28. First groove; 211. Receiving groove; 212. Limiting part; 213. Second L-shaped groove; 214. First L-shaped main body; 215. Second L-shaped main body; 221. Piezoelectric actuator; 222. Preload shim; 231. Offset flexible main body; 232. Arc anchoring part; 233. Driven part; 234. Offset flexible thin beam. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figures 1 to 3 , Figure 6 As shown, a bias-driven, weakly coupled two-dimensional precision motion platform includes a fixed base 1 and a two-dimensional motion platform 2, with the two-dimensional motion platform 2 disposed on the top surface of the fixed base 1. The two-dimensional motion platform 2 includes an intermediate platform 20, a platform body 21, a piezoelectric drive unit 22, a biased flexible amplification unit 23, and a sensor 24. The platform body 21 is disposed on the top surface of the fixed base 1. The intermediate platform 20 is located inside the platform body 21, and the intermediate platform 20 and the platform body 21 are integrally formed. Two receiving slots 211 are formed on the platform body 21 near one vertex of the intermediate platform 20. The two receiving slots 211 are orthogonally arranged. The two piezoelectric drive units 22 are respectively disposed in the receiving slots 211. The output end of element 22 is adapted to one end of the corresponding bias flexible amplification unit 23. The two bias flexible amplification units 23 are set on the platform body 21, and the other end of the bias flexible amplification unit 23 is connected to the intermediate platform 20. Two sensors 24 are respectively set on two adjacent sides of the intermediate platform 20 to measure the displacement of the two sides of the intermediate platform 20. Each sensor 24 is located on the same side of the intermediate platform 20 as the output end of the corresponding piezoelectric drive unit 22. The piezoelectric drive unit 22 drives the corresponding bias flexible amplification unit 23 to operate.

[0029] When sensor 24 detects displacement of intermediate platform 20, external controller receives the displacement and converts it into a drive command, and then sends the drive command to the corresponding piezoelectric drive unit 22. The piezoelectric drive unit 22 drives the bias flexible amplification unit 23 to perform an actuation displacement in the opposite direction to suppress the displacement of intermediate platform 20 after vibration.

[0030] The biased flexible amplification unit 23 includes a biased flexible main body 231, an arc-shaped anchoring part 232, a driven part 233, and a biased flexible thin beam 234. One end of the arc-shaped anchoring part 232, one end of the driven part 233, and one end of the biased flexible thin beam 234 are all connected to the same side of the biased flexible main body 231. The other end of the arc-shaped anchoring part 232 is connected to the platform main body 21, and the other end of the biased flexible thin beam 234 is connected to the intermediate platform 20. The biased flexible thin beam 234 is connected to the driven part... 233 is located on both sides of the center line of the intermediate platform 20. The driven part 233 is located between the arc anchor part 232 and the biased flexible thin beam 234. The other end of the driven part 233 has a driving contact surface, which abuts against the output end of the corresponding piezoelectric drive unit 22 to receive the driving force transmitted along the axial direction of the driven part 233. When the piezoelectric drive unit 22 works, it pushes the biased flexible body 231 to translate through the driven part 233 to absorb the vibration of the intermediate platform 20.

[0031] When the offset flexible amplification unit 23 is working, it transmits the original parasitic torque to the intermediate platform 20 due to flexible force transmission and local equivalent rotation. In this working state, when the offset flexible amplification unit 23 is subjected to thrust, the offset flexible main body 231 moves, generating an equivalent small rotation angle, due to the fixed connection between the arc anchor 232 and the platform body 21. This application adds an offset flexible thin beam 234. Since the offset flexible thin beam 234 has an offset distance relative to the centerline of the intermediate platform 20, when this equivalent small rotation angle occurs, the offset flexible thin beam 234 will generate additional elastic deformation. The formula for calculating the amount of deformation is: ; In the formula, This is the amount of deformation. The offset distance of the offset flexible thin beam 234 relative to the centerline of the intermediate platform 20. To generate an equivalent small rotation angle for the movement of the biased flexible body 231, Therefore, the formula for calculating the additional restoring force generated by the biased flexible thin beam 234 is: ; In the formula, The additional restoring force generated by the biased flexible thin beam 234 The equivalent stiffness of the biased flexible thin beam 234 in the working direction is given by... An offset distance is set for the offset flexible thin beam 234 relative to the centerline of the intermediate platform 20. The offset flexible body 231 is moved to generate an equivalent small rotation angle.

[0032] Since this additional restoring force acts at a position off the center line, the formula for calculating the resulting compensating torque is: ; In the formula, To compensate for torque, The additional restoring force generated by the biased flexible thin beam 234 The equivalent stiffness of the biased flexible thin beam 234 in the working direction is given by... An offset distance is set for the offset flexible thin beam 234 relative to the centerline of the intermediate platform 20. The offset flexible body 231 is moved to generate an equivalent small rotation angle.

[0033] In this invention, the offset distance is selected with the design objective of ensuring that the compensated torque is equal to the original parasitic torque during operation. Therefore, the preferred formula for calculating the offset dimension is: ; In the formula, For offset dimensions, For the original parasitic torque, The equivalent stiffness of the biased flexible thin beam 234 in the working direction is given by... The offset flexible body 231 is moved to generate an equivalent small rotation angle.

[0034] The preferred offset size can be obtained from the optimized offset size calculation formula. From the original parasitic torque Equivalent stiffness of the offset flexible thin beam 234 And the equivalent minute turning angle during operation The matching result is jointly determined by the offset distance. Preferred offset size When working, the compensation torque formed by the biased flexible thin beam 234 is equal to the original parasitic torque, and the residual torque on the intermediate platform 20 is zero, thereby eliminating parasitic rotation. This causes the driven part 233 to push the biased flexible body 231 to drive the intermediate platform 20 to output motion, which is manifested as translational output in the target direction.

[0035] When the offset flexible thin beam 234 is a rectangular cross-section flexible beam, the calculation formula is: ; in, The equivalent stiffness of the biased flexible thin beam 234 in the working direction is given by... The elastic modulus of the biased flexible thin beam 234 is given by... The width of the offset flexible thin beam 234, The thickness of the biased flexible thin beam 234, The length of the biased flexible thin beam 234, It is proportional to. Therefore, the preferred offset size is... There is a clear relationship between the thickness of the biased flexible thin beam 234 and its structural parameters: when the thickness of the biased flexible thin beam 234 is... When increased, the equivalent stiffness of the biased flexible thin beam 234 Increasing the offset size allows us to meet the preferred offset size required to satisfy the same compensation conditions. Reduce the length of the biased flexible thin beam 234 When increased, equivalent stiffness Reducing the offset size allows us to meet the preferred offset size required to satisfy the same compensation conditions. Increase when the material's elastic modulus increases Increasing the size also helps to reduce the preferred offset size. Therefore, the offset size The final value should be determined in conjunction with the thickness, length, width, and material parameters of the offset flexible thin beam 234.

[0036] It should be noted that the above preferred offset dimensions This corresponds to the matching result during operation. In actual operation, the intermediate platform 20 may be under different drive amplitudes, different external disturbances, or different frequency bands, at which point the original parasitic torque... and equivalent small rotation angle It will change. Under this type of mismatched operating condition, the offset dimension... Although it no longer corresponds to the strictly matched state of "zero residual torque", it can still reduce the original parasitic torque, thereby suppressing parasitic rotation, improving the two-dimensional motion decoupling performance and improving the platform output stability.

[0037] Each of the apexes of the intermediate platform 20 is provided with a first L-shaped groove 27, and the platform body 21 is provided with a second L-shaped groove 213 near the first L-shaped groove 27. The corresponding first L-shaped groove 27 and second L-shaped groove 213 are arranged in parallel, and the corresponding first L-shaped groove 27 and second L-shaped groove 213 form a guide decoupling unit 26. When one piezoelectric drive unit 22 works, the biased flexible body 231 will rotate around the arc anchoring part 232, and the biased flexible thin beam 234 will drive the intermediate platform 20 to undergo slight deformation, which will affect the measurement of the sensor 24 in another degree of freedom direction. Therefore, the guide decoupling unit 26 not only plays the role of positioning and limiting the intermediate platform 20, but also constrains the non-target motion degree of freedom.

[0038] The platform body 21, the biased flexible amplification unit 23, and the intermediate platform 20 are integrally formed.

[0039] The width of the first L-shaped groove 27 and the second L-shaped groove 213 is 0.2 mm.

[0040] Both the first L-shaped groove 27 and the second L-shaped groove 213 have right-angle features, which can determine the initial position or reference position of the intermediate platform 20 relative to the platform body 21. The physical boundaries of the first L-shaped groove 27 and the second L-shaped groove 213 limit the range of movement of the intermediate platform 20, preventing it from undergoing excessive displacement and deviating from the predetermined track or damaging the structure. Since the first L-shaped groove 27 and the second L-shaped groove 213 are arranged in parallel and used in conjunction, they form a kinematic pair, which allows the intermediate platform 20 to perform the expected small deformation or movement (i.e., the target degree of freedom). At the same time, the sidewalls and bottoms of the first L-shaped groove 27 and the second L-shaped groove 213 physically block the displacement of the intermediate platform 20 in other directions. For example, if the intermediate platform 20 attempts to slide to the side or undergo unnecessary torsion, the vertical surfaces of the first L-shaped groove 27 and the second L-shaped groove 213 will provide a reaction force to restrain it.

[0041] The first L-shaped groove 27 and the second L-shaped groove 213 cooperate to form a guiding decoupling unit 26. The guiding decoupling unit 26, through the physical limiting effect of the groove walls of the first L-shaped groove 27 and the second L-shaped groove 213, rigidly constrains the rotation of the intermediate platform 20 around the vertical axis and the translation in the non-target direction, thereby limiting the non-target degree of freedom of the intermediate platform 20. This ensures that when the piezoelectric drive unit 22 is working, the guiding decoupling unit 26 can forcibly limit the deformation of the bias flexible amplification unit 23 to the translation direction, suppressing the influence of the non-target degree of freedom, ensuring the measurement accuracy of the sensor 24 in this direction, and guaranteeing the two-degree-of-freedom translation output of the two-dimensional motion platform. This not only ensures the measurement accuracy of the sensor 24 in this translation direction, but also eliminates the crosstalk influence of the displacement in the non-target direction on the sensor 24 in other directions, thereby ultimately realizing the pure translation output of the intermediate platform 20 in the two-dimensional plane and completing the motion decoupling.

[0042] The arc anchoring part 232 is used to fix it to the platform body 21 and serves as the constraint base when the biased flexible amplification unit 23 undergoes elastic deformation; the driven part 233 is used to cooperate with the output end of the corresponding piezoelectric drive unit 22 to receive the drive displacement output by the piezoelectric drive unit 22; the biased flexible thin beam 234 realizes displacement transmission and motion conversion through its own elastic deformation under the driving action of the piezoelectric drive unit 22.

[0043] When the piezoelectric drive unit 22 generates axial elongation displacement under the action of the drive signal, its output end transmits this small displacement to the driven part 233 of the biased flexible amplification unit 23. After being pushed, the driven part 233 causes the biased flexible thin beam 234 to undergo elastic deformation. Since one end of the biased flexible thin beam 234 is connected to the arc anchoring part 232, and the arc anchoring part 232 constrains the biased flexible body 231, and at the same time, the biased flexible thin beam 234 is provided with a preferred bias size relative to the center line of the intermediate platform 20. Therefore, the overall deformation of the biased flexible amplification unit 23 is manifested as a translational displacement generated with the area where the arc anchoring part 232 is located as the constraint basis. This translational displacement acts on the intermediate platform 20 to compensate for its linear displacement, thereby achieving the purpose of maintaining platform stability and suppressing vibration.

[0044] Two biased flexible amplification units 23 are used to achieve micro-displacement movements in two directions. Since the two sets of piezoelectric drive units 22 and biased flexible amplification units 23 are arranged along two orthogonal directions, the present invention can achieve independent or linked drive in two directions in a plane.

[0045] The piezoelectric drive unit 22 includes a piezoelectric actuator 221 and a pre-tightening pad 222. The piezoelectric actuator 221 is embedded in the receiving groove 211. The output end of the piezoelectric actuator 221 is bonded to the pre-tightening pad 222. The pre-tightening pad 222 is in contact with the driven part 233. The actuation displacement output by the piezoelectric actuator 221 pushes the driven part 233 to move through the pre-tightening pad 222.

[0046] The piezoelectric actuator 221 acts as a drive source, outputting a small axial displacement under the action of an external control electrical signal. The preload shim 222 is used to apply axial preload to the piezoelectric actuator 221 in the assembled state, so that the piezoelectric actuator 221 always maintains a stable fit and reliable force during operation, avoiding the impact on driving accuracy and output stability due to gaps, looseness, or uneven force.

[0047] The end of the preload shim 222 that contacts the driven part 233 has a spherical structure. That is, a spherical rolling connection is formed between the preload shim 222 and the driven part 233 to improve the self-adaptive ability of the preload shim 222 in contact with the piezoelectric actuator 221, so that the preload shim 222 and the driven part 233 are kept in contact, reducing the off-center load phenomenon caused by installation errors or imperfect parallelism of the contact surfaces, so that the preload force can be applied to the piezoelectric actuator 221 more evenly, and it is beneficial to ensure that the piezoelectric actuator 221 outputs stable displacement along the predetermined output direction.

[0048] In actual operation, when the piezoelectric actuator 221 in the piezoelectric drive unit 22 generates an axial elongation displacement under the action of the drive signal, its output end transmits the displacement to the driven part 233 of the biased flexible amplification unit 23 through the preload shim 222. The driven part 233, under the action of thrust, causes the biased flexible thin beam 234 to undergo elastic deformation, and then transmits the displacement to the intermediate platform 20 through the biased flexible thin beam 234. Since the biased flexible thin beam 234 has already formed a compensating torque corresponding to the original parasitic torque through its bias dimension during operation, the drive in this direction mainly forms a linear displacement output in the target direction, without causing significant parasitic rotation in the intermediate platform 20. The two piezoelectric drive units 22 operate in the same way, used to achieve micro-displacement drive in two directions.

[0049] When only one piezoelectric drive unit 22 is working, the biased flexible body 231 mainly outputs micro-displacement along the first direction; when only the other piezoelectric drive unit 22 is working, the biased flexible body 231 mainly outputs micro-displacement along the second direction; when both sets of piezoelectric drive units 22 are working simultaneously, the micro-displacements output by the two biased flexible bodies 231 suppress the displacement of the intermediate platform 20 in both directions. During this process, the biased flexible amplification unit 23 forms a first-layer parasitic rotation compensation mechanism, pushing the biased flexible body 231 to translate via the driven part 233 to absorb the vibration of the intermediate platform 20. Simultaneously, the guiding decoupling unit 26 constitutes a second-layer non-target degree-of-freedom constraint mechanism. With this dual-action mechanism, the intermediate platform 20 can effectively suppress vibration and maintain high motion purity during two-dimensional motion, thereby reducing attitude deviation and improving repeatability and control linearity.

[0050] The platform body 21 includes a first L-shaped body 214 and a second L-shaped body 215. The horizontal and vertical parts of the first L-shaped body 214 are of equal length, and the horizontal and vertical parts of the second L-shaped body 215 are of equal length. The horizontal part of the first L-shaped body 214 is longer than the horizontal part of the second L-shaped body 215. The first L-shaped body 214 and the second L-shaped body 215 are respectively fixed on two areas diagonally distributed on the top surface of the fixed base 1. The other ends of the two arc anchoring parts 232 are respectively connected to the two ends of the first L-shaped body 214. Two offset flexible thin beams 234 are respectively set close to the two ends of the second L-shaped body 215. The first L-shaped body 214, the second L-shaped body 215 and the two offset flexible bodies 231 are arranged around the intermediate platform 20. The second L-shaped groove 213 is opened on the first L-shaped body 214 and the second L-shaped body 215.

[0051] When the piezoelectric actuator 221 outputs axial displacement, the driven part 233 transmits this displacement to the biased flexible thin beam 234, causing it to elongate and deform. In the biased flexible amplification unit 23, this deformation is mechanically manifested as a slight rotational tendency of the biased flexible body 231 around the arc anchoring part 232. Since one end of the biased flexible body 231 is connected and fixed to the first L-shaped body 214 through the arc anchoring part 232 and the slight rotational tendency is counteracted by the bias size, the driven part 233 transmits the displacement to the biased flexible thin beam 234 through the biased flexible body 231. The biased flexible thin beam 234 undergoes expansion and contraction deformation, and moves in a translational motion after being subjected to overall force with the biased flexible body 231, converting the slight axial displacement output by the piezoelectric actuator 221 into a displacement that restricts the movement of the intermediate platform 20.

[0052] The first L-shaped main body 214 provides lateral support and motion guidance when the offset flexible thin beam 234 undergoes flexible deformation, restricts the directional deflection of non-working degrees of freedom, and avoids attitude disturbance caused by working motion.

[0053] This invention achieves efficient transmission, displacement amplification, and degree-of-freedom decoupling of two-dimensional micro-displacement under piezoelectric drive through the compact arrangement of the first L-shaped main body 214, the second L-shaped main body 215, and two biased flexible main bodies 231 around the intermediate platform 20, combined with the biased arrangement of the biased flexible thin beam 234 and the multi-point constraint of the guide decoupling unit 26. This provides a high-precision two-dimensional motion platform with a compact structure, stable motion, and good decoupling performance for semiconductor manufacturing equipment.

[0054] The piezoelectric actuator 221 is embedded in the receiving groove 211. The groove wall of the receiving groove 211 provides installation positioning and lateral limiting for the piezoelectric actuator 221, ensuring that the piezoelectric actuator 221 stably outputs axial displacement in a predetermined direction. Since the receiving groove 211 is located on the horizontal and vertical parts of the first L-shaped main body 214 and close to the end of the biased flexible main body 231, the output end of the piezoelectric actuator 221 can directly act on the biased flexible main body 231, resulting in a short driving force transmission path and low loss.

[0055] The two receiving slots 211 are arranged perpendicularly, so that the output directions of the two piezoelectric actuators 221 are orthogonal to each other, corresponding to two motion directions in a two-dimensional plane. Since one end of the biased flexible body 231 is connected to the first L-shaped body 214 through the arc anchor 232, and the other end is set close to the second L-shaped body 215, the translation of the biased flexible body 231 converts the small axial displacement of the piezoelectric actuator 221 into a driving displacement of the intermediate platform 20.

[0056] The end of the first L-shaped main body 214 has a limiting part 212, which is perpendicular to the end of the first L-shaped main body 214 and is located between the corresponding biased flexible main body 231 and the first L-shaped main body 214.

[0057] The four sides of the intermediate platform 20 are all recessed inward to form a first groove 28. A first L-shaped groove 27 is formed on the intermediate platform 20 near the first L-shaped body 214, the second L-shaped body 215 and the limiting part 212. A second L-shaped groove 213 is formed on the first L-shaped body 214, the second L-shaped body 215 and the limiting part 212 near the intermediate platform 20.

[0058] By adding a limiting part 212, it can be ensured that all four vertices of the intermediate platform 20 have a guide decoupling unit 26 formed by the first L-shaped groove 27 and the second L-shaped groove 213. The four guide decoupling units 26 effectively constrain the non-target degrees of freedom of the intermediate platform 20, which is used to suppress the additional rotational tendency and parasitic motion transmitted to the intermediate platform 20 due to the rotational deformation of the biased flexible body 231, improve the independence between the two motion directions, reduce the coupling effect between the driving branches in different directions, and enable the intermediate platform 20 to have better decoupling performance and higher control accuracy when realizing two-dimensional motion.

[0059] like Figures 1 to 4 As shown, the two-dimensional motion platform 2 also includes a sensor mounting base 25. One end of the sensor 24 is located near the bottom of the first groove 28. The first groove 28 extends to the top and bottom surfaces of the intermediate platform 20, respectively. The bottom of the first groove 28 serves as the detection surface for the sensor 24 to detect the displacement of the intermediate platform 20. The other end of the sensor 24 is mounted on the sensor mounting base 25, and the bottom of the sensor mounting base 25 is mounted on the fixed base 1.

[0060] Two sensors 24 are used to detect, provide feedback or measure displacement signals in corresponding directions, so as to monitor the motion state of the intermediate platform 20 and provide a basis for the precision control and performance testing of the intermediate platform 20.

[0061] Sensor 24 is electrically connected to the input terminal of an external controller via a signal line, and piezoelectric actuator 221 is electrically connected to the output terminal of an external controller via a drive line.

[0062] like Figures 1 to 3 , Figure 5 As shown, the top surface of the fixed base 1 is recessed inward near the offset flexible body 231 to form a second groove 11, which extends to the side of the fixed base 1; a square through groove 12 is provided on the top surface of the fixed base 1 and corresponding to the position of the intermediate platform 20; a third groove 13 is recessed inward on the side wall of the square through groove 12 near the sensor 24; the bottom of the sensor mounting base 25 is mounted on the bottom of the third groove 13.

[0063] The second groove 11 provides clearance for the flexible deformation of the biased flexible body 231, preventing interference between the biased flexible body 231 and the fixed base 1 during large-stroke deformation, and ensuring that the biased flexible amplification unit 23 has sufficient deformation stroke. Simultaneously, the second groove 11 reduces the local thickness of the fixed base 1 in this area, appropriately lowering the local stiffness, which is beneficial for the biased flexible body 231 to obtain smoother deformation characteristics. A square through-slot 12 is formed on the top surface of the fixed base 1 and corresponds to the position of the intermediate platform 20. The length and width of the square through-slot 12 are both greater than the length and width of the intermediate platform 20, providing space for the two-dimensional movement of the intermediate platform 20. This prevents the intermediate platform 20 from colliding or rubbing against the fixed base 1 when moving in orthogonal directions in the horizontal plane, ensuring the smoothness of the movement and the integrity of the stroke of the intermediate platform 20.

[0064] By embedding the sensor mounting base 25 into the third groove 13, the detection distance between the sensor 24 and the intermediate platform 20 is shortened, enabling the sensor 24 to more accurately sense the vibration signals and displacement changes of the intermediate platform 20. Furthermore, the third groove 13 provides mounting positioning and lateral restraint for the sensor mounting base 25, ensuring the accuracy and repeatability of the sensor 24's mounting position, thereby improving the accuracy and reliability of displacement detection. The second groove 11 and the square through slot 12 provide ample deformation and movement space for the moving parts, while the third groove 13 optimizes the mounting positioning of the sensor 24. The combined effect of these three elements ensures the smooth movement, detection accuracy, and structural reliability of the intermediate platform 20.

[0065] The matching sensor 24 and sensor mounting base 25 are respectively installed in the corresponding first groove 28 and third groove 13. The two sensors 24 are installed in the first groove 28 on two perpendicular sides of the intermediate platform 20, and are used to detect the displacement change or vibration response of the intermediate platform 20 in two orthogonal directions in real time. After the output signal of the sensor 24 is input to the external controller, the external controller can output a compensation drive voltage to the corresponding piezoelectric actuator 221 according to the detected displacement deviation, velocity signal or vibration error signal, so that the piezoelectric actuator 221 generates a reverse compensation displacement to offset the displacement deviation caused by external disturbance or the micro-vibration of the intermediate platform 20 itself, thereby realizing active vibration isolation, active vibration suppression or closed-loop micro-displacement control of the intermediate platform 20.

[0066] This invention introduces an offset flexible amplification unit 23 and a guiding decoupling unit 26 into a two-dimensional motion platform 2. On the one hand, by utilizing the offset setting of the offset flexible thin beam 234 and its matching relationship with the stiffness parameters, the compensation torque is made equal to the original parasitic torque during operation, thereby eliminating parasitic rotation. On the other hand, the guiding decoupling unit 26, located at the apex of the intermediate platform 20, further constrains the non-target degrees of freedom, improving the motion independence and overall stability between the two orthogonal directions. Simultaneously, combined with sensors 24 arranged on the two mutually perpendicular sides of the intermediate platform 20, it not only achieves high-precision two-dimensional micro-displacement output but also enables active vibration isolation and vibration compensation in the two-dimensional direction. This is suitable for applications requiring high precision, low coupling, and high stability, such as semiconductor manufacturing, precision testing, micro-assembly, and other applications.

[0067] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A bias-driven, weakly coupled two-dimensional precision motion platform, comprising a fixed base and a two-dimensional motion platform, wherein the two-dimensional motion platform is disposed on the top surface of the fixed base, characterized in that: The two-dimensional motion platform includes an intermediate platform, a platform body, a piezoelectric drive unit, a biased flexible amplification unit, and a sensor. The intermediate platform is located inside the platform body. Two receiving slots are formed on the platform body near one vertex of the intermediate platform. The two receiving slots are orthogonally arranged. The two piezoelectric drive units are respectively set in the corresponding receiving slots. Each piezoelectric drive unit is adapted to one end of the corresponding biased flexible amplification unit, and the other end of the biased flexible amplification unit is connected to the intermediate platform. The two sensors are respectively mounted on two adjacent sides of the middle platform; The biased flexible amplification unit includes a biased flexible body, an arc anchoring part, a driven part, and a biased flexible thin beam. One end of the arc anchoring part, one end of the driven part, and one end of the biased flexible thin beam are all connected to the same side of the biased flexible body. The other end of the arc anchoring part is connected to the platform body, and the other end of the biased flexible thin beam is connected to the intermediate platform. The biased flexible thin beam and the driven part are located on both sides of the center line of the intermediate platform. The driven part is located between the arc anchoring part and the biased flexible thin beam. The other end of the driven part has a driving contact surface, which abuts against the output end of the corresponding piezoelectric driving unit to receive the driving force transmitted along the axial direction of the driven part. Each of the apexes of the intermediate platform is provided with a first L-shaped groove, and a second L-shaped groove is provided on the main body of the platform near the first L-shaped groove. The corresponding first L-shaped groove and second L-shaped groove form a guide decoupling unit.

2. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 1, characterized in that: The distance between the offset flexible thin beam and the corresponding centerline on the intermediate platform is the offset dimension, and the formula for calculating the offset dimension is: ； In the formula, For offset dimensions, To transmit the original parasitic torque to the intermediate platform, The equivalent stiffness of the biased flexible thin beam. This is the equivalent minute rotation angle corresponding to the biased flexible amplification unit during operation.

3. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 1, characterized in that: The width of both the first L-shaped groove and the second L-shaped groove is 0.2 mm.

4. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 1, characterized in that: The piezoelectric drive unit includes a piezoelectric actuator and a pre-tightening pad. The piezoelectric actuator is embedded in the receiving groove. The output end of the piezoelectric actuator is bonded to the pre-tightening pad. The pre-tightening pad is in contact with the driven part. The piezoelectric actuator pushes the driven part to move through the pre-tightening pad.

5. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 4, characterized in that: The end of the pre-tightening pad that contacts the driven part has a spherical structure, which improves the adaptability of the pre-tightening pad in contact with the driven part.

6. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 5, characterized in that: The platform body includes a first L-shaped body and a second L-shaped body. The horizontal and vertical parts of the first L-shaped body are of equal length, and the horizontal and vertical parts of the second L-shaped body are of equal length. The horizontal part of the first L-shaped body is longer than the horizontal part of the second L-shaped body. The first L-shaped body and the second L-shaped body are respectively fixed to two diagonally distributed areas on the top surface of the fixed base. The other ends of the two arc anchoring parts are respectively connected to the two ends of the first L-shaped body. The two offset flexible thin beams are respectively arranged close to the two ends of the second L-shaped body. The first L-shaped body, the second L-shaped body, and the two offset flexible bodies are arranged around the intermediate platform. The second L-shaped groove is formed on the first L-shaped body and the second L-shaped body. When the piezoelectric actuator outputs axial displacement, the driven part transmits the axial displacement to the biased flexible thin beam. One end of the biased flexible body is connected and fixed to the first L-shaped body through the arc anchoring part. The driven part transmits the axial displacement to the biased flexible thin beam through the biased flexible body. The biased flexible thin beam undergoes expansion and contraction deformation and moves in a translational motion with the biased flexible body after being subjected to force as a whole, converting the axial displacement output by the piezoelectric actuator into a displacement that restricts the movement of the intermediate platform.

7. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 6, characterized in that: The end of the first L-shaped body has a limiting part, which is perpendicular to the end of the first L-shaped body and is located between the corresponding biased flexible body and the first L-shaped body.

8. The bias-driven, weakly coupled two-dimensional precision motion platform according to claim 7, characterized in that: The four sides of the intermediate platform are all recessed inward to form a first groove; The first L-shaped groove is formed on the intermediate platform near the first L-shaped body, the second L-shaped body and the limiting part, and the second L-shaped groove is formed on the first L-shaped body, the second L-shaped body and the limiting part near the intermediate platform.

9. A bias-driven, weakly coupled two-dimensional precision motion platform according to claim 8, characterized in that: The two-dimensional motion platform also includes a sensor mounting base. One end of the sensor is located near the bottom of the first groove, and the other end of the sensor is mounted on the sensor mounting base. The bottom of the sensor mounting base is mounted on the fixed base. The sensor is used for the detection, feedback, or measurement of displacement signals in the corresponding direction, so as to monitor the motion state of the intermediate platform in real time.

10. A bias-driven, weakly coupled two-dimensional precision motion platform according to claim 9, characterized in that: The top surface of the fixed base is recessed inward near the offset flexible body to form a second groove, which extends to the side of the fixed base. A square through slot is formed on the top surface of the fixed base, corresponding to the position of the intermediate platform. A third groove is formed on the side wall of the square through slot near the sensor. The bottom of the sensor mounting base is mounted on the bottom of the third groove, which shortens the detection distance between the sensor and the intermediate platform, enabling the sensor to more accurately sense the vibration signal and displacement change of the intermediate platform.

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