Linear motion stage

Abstract

The application relates to a linear motion table, comprising a linear actuator, an annular outer ring, an annular inner ring and a leaf spring, the annular outer ring and the annular inner ring are coaxially arranged, the leaf spring is fixedly connected between the annular outer ring and the annular inner ring, the linear actuator is arranged on the inner side of the annular inner ring and is fixedly connected with a base table, one of the annular outer ring and the annular inner ring is fixedly connected with the base table, the other is connected with a load table, and the movement shaft of the linear actuator is connected with the load table. The application has the advantages of compact structure, small volume, improved anti-interference performance of the motion table to inertial force, improved working stability and reliability of the linear motion table.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision positioning control, in particular to a linear motion table. BACKGROUND

[0002] In the product detection, in order to ensure the accuracy of detection, according to the different working conditions, the measured object can be precisely positioned by the linear motion table, or the measured object can be precisely positioned by combining the XY motion table and the Z direction motion table arranged on the XY motion table, and the position of the measured object is adjusted in the case of the demand of the specific working condition. And for different product types, the working precision requirements of the motion table are different, and when the semiconductor wafer is detected, the detection precision requirement is higher due to its own structural precision, even to micron or nanometer level.

[0003] As for the Z direction linear motion table, the voice coil motor is currently used as the driving element, but the whole Z direction motion table has the problems of low control bandwidth, large heat generation and strong magnetic field. The magnetic field will affect the electron microscope scanning, and will also affect the objective lens scanning rate during the semiconductor wafer detection, and the generation of large heat will also cause the thermal deformation of the detected semiconductor wafer, affecting the product yield.

[0004] Therefore, how to optimize the structure of the single degree of freedom linear motion table in the Z direction to better meet the high stiffness and high precision requirements of the semiconductor wafer detection is a technical problem to be solved at present. SUMMARY

[0005] The purpose of the present application is to provide a linear motion table, which has compact structure, small volume, can improve the anti-interference of the motion table to the inertial force, and improve the working stability and reliability of the linear motion table.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0007] The present application provides a linear motion table, which comprises a linear actuator, a ring-shaped outer ring, a ring-shaped inner ring and a leaf spring, the ring-shaped outer ring and the ring-shaped inner ring are coaxially arranged, and the leaf spring is fixedly connected between the ring-shaped outer ring and the ring-shaped inner ring, the linear actuator is arranged on the inner side of the ring-shaped inner ring and is fixedly connected with the base table, one of the ring-shaped outer ring and the ring-shaped inner ring is fixedly connected with the base table, and the other is connected with the load table surface, and the movement shaft of the linear actuator is connected with the load table surface.

[0008] For the above technical scheme, the applicant has further optimization measures.

[0009] Optionally, the top of the annular outer ring is fixedly connected with the bottom of the load platform, and the bottom of the annular inner ring is fixedly connected with the surface of the base.

[0010] Optionally, the movement axis of the linear actuator is connected with the load platform through a flexible hinge.

[0011] Optionally, the flexible hinge is a double-ring structure, the inner ring is fixedly connected with the movement axis of the linear actuator, and the outer ring is fixedly connected with the load platform.

[0012] Optionally, two layers of leaf springs are arranged between the annular outer ring and the annular inner ring, and the two layers of leaf springs are arranged in the radial direction.

[0013] Further, the linear actuator is fixedly connected with the annular inner ring.

[0014] Optionally, the base is a fixed platform or a rotating platform of a rotating motion platform.

[0015] Thanks to the above technical solution, the present application has the following advantages compared with the prior art:

[0016] The linear motion platform has a compact overall structure and a small device volume, the double-layer leaf spring is matched with the double-ring nested annular outer ring and annular inner ring structure, so that the linear motion platform has better rigidity in the other two rotating directions, the linear actuator and the load platform are connected through the flexible hinge, the lateral force and lateral torque borne by the linear actuator are reduced, the motion accuracy of the linear actuator is not affected, the rigidity and accuracy in the linear direction are improved, and the working stability and reliability of the motion platform are improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings in an exemplary and non-limiting manner. The same reference signs in the drawings denote the same or similar components or parts. Those skilled in the art should understand that the drawings are not necessarily drawn to scale. In the drawings:

[0018] Figure 1 is a schematic diagram of the overall structure of a linear motion platform according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of the cross-sectional structure of a linear motion platform (with a load platform) according to an embodiment of the present application.

[0020] The reference signs are as follows:

[0021] 1, base, 2, linear actuator, 3, annular outer ring, 31, outer compression ring, 4, annular inner ring, 41, inner compression ring, 5, leaf spring, 6, flexible hinge, 7, load platform. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0023] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0024] The present embodiment describes a linear motion table which is arranged on the surface of a base table 1, which can be one of a fixed table or a rotating table of a rotary motion table. That is, the linear motion table can be directly arranged on a fixed table to realize linear motion in a single direction; the linear motion table can also be arranged on the rotating table of a rotary motion table to realize adjustable motion in two degrees of freedom of Z and RZ. The specific working condition can be adjusted according to user requirements, and in the present embodiment, the linear motion table arranged on the fixed table is realized. As for the arrangement on the rotating table, those skilled in the art can analogize and it is not described here. Please be aware.

[0025] As shown in Figure 1 , Figure 2 The linear motion table of the present embodiment can include a linear actuator 2, an annular outer ring 3, an annular inner ring 4, and a leaf spring 5. The annular outer ring 3 and the annular inner ring 4 are coaxially arranged and fixedly connected between the annular outer ring 3 and the annular inner ring 4. The linear actuator 2 is arranged on the inner side of the annular inner ring 4 and fixedly connected with the base table 1. One of the annular outer ring 3 and the annular inner ring 4 is fixedly connected with the base table 1, and the other is connected with the load table 7. The movement shaft of the linear actuator 2 is connected with the load table 7.

[0026] From the perspective of realizing basic functions, the linear motion table of the present embodiment will not affect the action of the linear actuator 2 whether the annular outer ring 3 is fixedly connected with the base table 1, the annular inner ring 4 is fixedly connected with the load table 7, or the annular inner ring 4 is fixedly connected with the base table 1, and the annular outer ring 3 is fixedly connected with the load table 7, because the linear actuator 2 is connected with the load table 7. The load table 7 moves under the drive of the linear actuator 2. By selecting a high-precision drive mechanism such as a piezoelectric ceramic linear actuator 2, the motion accuracy can reach the nanometer level. In addition, the piezoelectric ceramic linear actuator 2 has the characteristics of high precision, high control bandwidth, no magnetism, small heating, sub-millisecond response time, small size, and high output. When the motor is not powered, it has a stiffness much higher than that of a voice coil motor.

[0027] From the aspects of convenient installation and driving reliability, in the embodiment, the top of the annular outer ring 3 is fixedly connected with the bottom of the load table 7, the bottom of the annular inner ring 4 is fixedly connected with the surface of the base 1, and the movement shaft of the linear actuator 2 is connected with the load table 7 through the flexible hinge 6 structure. The diameter of the annular outer ring 3 is large, and the annular outer ring 3 can give more uniform force to the load table 7 when the linear actuator 2 moves, because the linear actuator 2 pushes and pulls in the middle of the load table 7, and the annular outer ring 3 gives reverse pulling force from the periphery, so that the overall movement of the load table 7 is more stable.

[0028] The linear motion table of the embodiment has a compact overall structure and small equipment volume, and adopts the double-layer plate spring 5 to cooperate with the double-ring nested annular outer ring 3 and annular inner ring 4 structure, so that the linear motion table has better rigidity in the other two rotation directions.

[0029] For the fixation of the plate spring 5, the embodiment is to fix the two layers of plate springs 5 at the top and bottom of the annular outer ring 3 and the annular inner ring 4 through the pressing ring (outer pressing ring 31 and inner pressing ring 41), the top and bottom of the annular outer ring 3 are respectively fixed by an outer pressing ring to form a three-layer structure, and the top and bottom of the annular inner ring 4 are respectively fixed by an inner pressing ring to also form a three-layer structure.

[0030] Actually, the plate spring 5 can also be fixed between the annular outer ring 3 and the annular inner ring 4 by laser welding or other fixing methods (such as a clamping groove, a boss combined with a screw fastening, etc.), of course, the combination of the pressing ring fixation and the above laser welding or other fixing methods can also be adopted, as long as the plate spring 5 can be fixed between the annular outer ring 3 and the annular inner ring 4. Correspondingly, according to whether the pressing ring exists or not, or whether the single pressing ring or the upper and lower double pressing rings exist, it can be understood that the annular outer ring 3 and the annular inner ring 4 are designed as a single-layer, double-layer or three-layer structure.

[0031] The linear actuator 2 and the load table 7 are connected through the flexible hinge 6, which can reduce the lateral force and lateral moment suffered by the linear actuator 2, ensure that the movement accuracy of the linear actuator 2 is not affected, thereby improving the rigidity and accuracy of the linear motion table in the linear direction, and improving the working stability and reliability of the motion table.

[0032] Specifically, the flexible hinge 6 is a double ring structure, including an inner ring structure and an outer ring structure, both of which are circular bosses, the outer diameter of the boss of the inner ring structure is equal to the inner ring of the boss of the outer ring structure, the boss of the inner ring structure has a radial through groove but still has a connecting edge so as not to be disconnected, similarly, the boss of the outer ring structure has a radial through groove but still has a connecting edge so as not to be disconnected. When assembled, the inner ring structure and the outer ring structure are butted together, and the through grooves on the two structures are located in the same plane after butting. The seat of the inner ring structure is fixedly connected with the movement shaft of the linear actuator 2, and the seat of the outer ring structure is fixedly connected with the load table 7.

[0033] In order to improve the rigidity between the annular outer ring 3 and the annular inner ring 4 in the RX and RY directions, two layers of plate springs 5 are arranged between the annular outer ring 3 and the annular inner ring 4, which are arranged in the radial direction. In order to improve the rigidity, the two layers of plate springs 5 need to be arranged with the largest possible spacing, but the spacing of the two layers of plate springs 5 cannot be too large, and the spacing of the two layers of plate springs 5 needs to be able to ensure that the rigidity between the annular outer ring 3 and the annular inner ring 4 does not affect the Z-direction deformation, and the control of the Z-direction deformation amount can be realized. Because the plate spring 5 with too large spacing provides stronger Z-direction rigidity, the first linear actuator cannot effectively promote the Z-direction deformation to adjust the position of the load table when it is in action. If the Z-direction rigidity is high, a larger force motor will be needed under the same displacement. Similarly, the Z-direction rigidity is high, so the displacement will be small under the same motor. Therefore, in order to ensure that the displacement of the Z-direction under the action of the first linear actuator can meet the measurement requirements, the spacing of the double-layer plate spring 5 is as large as possible.

[0034] In addition, the linear actuator 2 is fixedly connected with the annular inner ring 4 in the embodiment. The linear actuator 2 can also be fixed with the base 1. For the butt joint fixing of the linear motion table and the rotary motion table, the linear actuator 2 can be fixed with the rotary table of the rotary motion table, so that the linear motion table as a whole can rotate together with the rotary table in the RZ direction.

[0035] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A linear motion table, characterized in that, The device includes a linear actuator, an outer annular ring, an inner annular ring, and leaf springs. The outer annular ring and the inner annular ring are coaxially arranged, and the leaf springs are fixedly connected between the outer annular ring and the inner annular ring. The linear actuator is disposed inside the inner annular ring and fixedly connected to a base. One of the outer annular ring and the inner annular ring is fixedly connected to the base, while the other is connected to a load platform. The motion shaft of the linear actuator is connected to the load platform. Two layers of leaf springs are disposed between the outer annular ring and the inner annular ring. The two layers of leaf springs are arranged radially and are fixed to the top and bottom of the outer annular ring and the inner annular ring, respectively, by pressure rings. The motion shaft of the linear actuator is connected to the load platform via a flexible hinge.

2. The linear motion table according to claim 1, characterized in that, The top of the outer annular ring is fixedly connected to the bottom of the load platform, and the bottom of the inner annular ring is fixedly connected to the base surface.

3. The linear motion table according to claim 1, characterized in that, The flexible hinge has a double-ring structure, with the inner ring fixedly connected to the motion axis of the linear actuator and the outer ring fixedly connected to the load platform.

4. The linear motion table according to any one of claims 1 to 3, characterized in that, The linear actuator is fixedly connected to the annular inner ring.

5. The linear motion table according to claim 1, characterized in that, The base is either a fixed platform or a rotating platform of a rotating motion platform.

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