Combined type six-degree-of-freedom lens unstressed supporting and adjusting device

Abstract

The invention discloses a combined type six-degree-of-freedom lens unstressed supporting and adjusting device, which relates to the technical field of precise optical adjustment and comprises a six-degree-of-freedom adjusting module and an unstressed supporting module. The six-degree-of-freedom adjusting module is composed of a base, a lower triangle and six flexible motion supporting legs based on an improved Scott-Russell mechanism, nanoscale displacement adjustment is achieved through driving of a piezoelectric actuator and a lever mechanism, and six-degree-of-freedom high-precision pose adjustment of the lens is completed in cooperation with closed-loop control of a capacitance displacement sensor. The stress-free supporting module adopts an integrated design of three groups of supporting arms with flexible hinges and a lens frame, precise positioning is realized through cooperation of a lens cushion block and a pressing block, and the influence of assembly stress and thermal deformation is effectively eliminated. According to the invention, the upper and lower structures work cooperatively, the nano-scale regulation capability and the environmental stability are realized, and the photoetching imaging quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of precision optical adjustment, and in particular to a compound six-degree-of-freedom stress-free support adjustment device for lenses, which is applicable to scenarios such as lithography projection objectives and high-resolution imaging systems that require nanoscale pose control. High-precision adjustment and stress self-adaptive release are achieved through the collaborative design of the upper and lower structures. Background Art

[0002] In the projection objective system of a lithography machine, the pose accuracy of optical lenses directly affects the resolution and overlay accuracy of lithography imaging. As the semiconductor process node continues to shrink, the positioning accuracy requirement for lenses has reached the sub-nanometer level. The traditional adjustment mechanism for lithography machine lenses mainly adopts a multi-point support structure with rigid connections, and there are the following technical bottlenecks: First, the stress generated during the mechanical assembly process will cause the surface shape distortion of the lens, affecting the optical wavefront quality; second, the heat accumulation generated by the continuous operation of the lithography machine will cause thermal deformation of the support structure, resulting in lens position drift; third, most of the existing six-degree-of-freedom adjustment mechanisms adopt a series structure, and there is coupling interference between each degree of freedom, making it difficult to achieve precise decoupling control. Especially in extreme ultraviolet lithography systems, any slight stress in the lens support structure will cause non-negligible aberrations. To address these problems, there is an urgent need to develop a new type of compound adjustment mechanism that can not only achieve nanoscale precision pose control but also effectively eliminate the influence of assembly stress and thermal deformation to meet the requirements of the advanced lithography process for the lens support system. Summary of the Invention

[0003] The present invention provides a compound six-degree-of-freedom stress-free support adjustment device for lenses, including a six-degree-of-freedom adjustment mechanism composed of a base, a lower triangle, and six flexible motion legs improved based on the principle of the Scott-Russell (SR) mechanism, and a stress-free support mechanism that integrates the support structure and the lens frame into one; wherein the base is connected to the projection objective support disk, the lower triangle is connected to the moving lens support ring, and the six flexible motion legs are evenly distributed in a circular pattern between the base and the lower triangle. They are driven by piezoelectric actuators and the displacement is reduced through an improved SR lever mechanism to achieve nanoscale control. With the closed-loop feedback control of a capacitive displacement sensor, high-precision six-degree-of-freedom pose adjustment of the lens is achieved; at the same time, the integrally designed stress-free support mechanism effectively eliminates the influence of assembly stress and thermal deformation through the collaborative cooperation of three groups of support arms with flexible hinges, lens pads, and lens pressing blocks, and the overall structure has both high-precision adjustment ability and excellent environmental stability.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A compound six-degree-of-freedom lens stress-free support adjustment device, comprising a six-degree-of-freedom lens adjustment mechanism and a stress-free support mechanism; the six-degree-of-freedom lens adjustment mechanism consists of a base, a lower triangle and six flexible motion legs distributed circumferentially; the stress-free support mechanism is connected to the six-degree-of-freedom lens adjustment mechanism through mounting holes provided on the stress-free support mechanism.

[0006] The beneficial effects of the present invention are as follows: on the one hand, the stress-free support mechanism effectively eliminates the influence of assembly stress and thermal deformation, improving the stability and reliability of the system. On the other hand, the integrated design reduces the assembly process, lowers the assembly cost while improving the assembly accuracy.

[0007] Furthermore, the displacement adjustment with nanometer-level precision is achieved by adopting an improved SR lever mechanism, and the high-precision coupling adjustment of the six degrees of freedom of the moving lens is completed in cooperation with six groups of independently controlled flexible motion legs. In addition, special materials with low expansion coefficients are selected to ensure the stability of the system when the temperature changes. The collaborative design of the upper and lower structures not only achieves nanometer-level precision adjustment but also greatly improves the environmental adaptability and lithography imaging quality of the system. Description of the Drawings

[0008] Figure 1 This is a compound six-degree-of-freedom lens stress-free support adjustment device provided by the present invention. Among them, 1 is the base, 2 is the flexible motion leg, 3 is the lower triangle, and 4 is the stress-free support mechanism;

[0009] Figure 2 This is a sectional view of the flexible motion leg. Among them, 2-1 is the flexible arm, 2-2 is the capacitive displacement sensor, and 2-3 is the piezoelectric actuator;

[0010] Figure 3 This is a schematic diagram of the flexible motion leg. Among them, 2-4 is the slotted cheesehead screw, 2-5 is the spring, and 2-6 is the socket head cap screw;

[0011] Figure 4 This is a schematic diagram of the flexible arm. Among them, 2-1-1 is the mounting hole of the flexible arm and the base, 2-1-2 is the mounting hole of the piezoelectric actuator, 2-1-3 is the mounting hole of the capacitive displacement sensor, 2-1-4 is the mounting hole of the slotted cheesehead screw, 2-1-5 is the mounting hole of the socket head cap screw, and 2-1-6 is two flexible hinges;

[0012] Figure 5 This is the stress-free support mechanism. Among them, 4-1 is the flexible support arm, 4-2 is the lens pad, 4-3 is the lens pressing block, 4-4 is the lens socket head cap screw, 4-5 is the flexible hinge, and 4-6 is the mounting hole;

[0013] Figure 6 This is the schematic diagram of the mechanism improved based on the principle of the Scott-Russell mechanism. Detailed implementation mode

[0014] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0015] Figure 1 A compound six-degree-of-freedom lens stress-free support adjustment device provided for the present invention. As Figure 1 shown, the device includes a six-degree-of-freedom lens adjustment mechanism and a stress-free support mechanism 4, wherein the six-degree-of-freedom lens adjustment mechanism is composed of a base 1, a lower triangle 3 and six flexible motion legs 2 distributed circumferentially; the stress-free support mechanism 4 is connected to the six-degree-of-freedom lens adjustment mechanism through an installation hole 4-6. The installation hole 4-6 is the installation hole for the stress-free support mechanism and the six-degree-of-freedom adjustment mechanism.

[0016] Among them, the upper part of the base 1 is connected to the projection objective lens support disk by, for example, screws. Six flexible motion legs 2 are arranged between the base 1 and the lower triangle 3. The lower part of the lower triangle 3 is connected to the stress-free support mechanism 4 by screws. Through the length coupling adjustment of the six flexible motion legs 2, the axial movement of the lower triangle 3 and the stress-free support mechanism 4 on the XYZ axes and the rotational movement around the XYZ axes are realized, thereby driving the moving lens to realize the six-degree-of-freedom pose adjustment.

[0017] Figure 2 Is the cross-sectional view of the flexible motion leg. Figure 3 Is the schematic diagram of the flexible motion leg. As Figure 2 、 Figure 3 shown, the flexible motion leg includes a flexible arm 2-1, a capacitive displacement sensor 2-2, and a piezoelectric actuator 2-3. Among them, the lower ball head of the piezoelectric actuator 2-3 is used as the driving point. By driving the piezoelectric actuator 2-3, the internal screw rod is elongated or shortened, so that the flexible arm 2-1 undergoes relative displacement. After the reduction conversion of the lever reduction mechanism, the total displacement is reduced, thereby completing the nano-level adjustment of the length of the flexible motion leg 2. The capacitive displacement sensor 2-2 feeds back the measured high-precision displacement signal to the piezoelectric actuator 2-3, and by adjusting the displacement driving amount in real time, the high-precision control of the length of the flexible motion leg 2 is achieved.

[0018] In one embodiment, the flexible motion leg further includes a slotted round head screw 2-4, a spring 2-5, and an Allen set screw 2-6. Among them, the spring 2-5 is hooked with two slotted round head screws 2-4 to provide pre-tightening stiffness for the flexible arm 2-1 and maintain a certain tensile force. Specifically, one slotted round head screw 2-4 is fastened to the slotted round head screw mounting hole 2-1-4, and the other slotted round head screw 2-4 is fastened to another slotted round head screw mounting hole 2-1-4 at the corresponding position. The spring 2-5 is hooked between the two slotted round head screws 2-4. The Allen set screw 2-6 is used to fasten the capacitive displacement sensor 2-2 to the flexible arm 2-1.

[0019] Figure 4 Schematic diagram of the flexible arm 2-1. As Figure 4 shown, the flexible arm 2-1 includes a flexible arm and a base mounting hole 2-1-1, a piezoelectric actuator mounting hole 2-1-2, a capacitive displacement sensor mounting hole 2-1-3, a slotted round head screw mounting hole 2-1-4, an Allen set screw mounting hole 2-1-5, and two flexible hinges 2-1-6.

[0020] Among them, the flexible arm 2-1 is connected to the base 1 through the flexible arm and the base mounting hole 2-1-1. The piezoelectric actuator 2-3 is connected to the flexible arm 2-1 through the piezoelectric actuator mounting hole 2-1-2 and forms an improved Scott-Russell (SR) lever mechanism with the flexible arm 2-1. The output displacement of the piezoelectric actuator 2-3 is reduced through the lever conversion to achieve a reduction in the total displacement, thereby completing the nanoscale adjustment of the length of the flexible motion leg 2. Among them, the improvement of the improved Scott-Russell (SR) lever mechanism compared with the traditional Scott-Russell (SR) lever mechanism is that: the fulcrum position of the flexible arm 2-1 is shifted from the midpoint to the output end, and three groups of flexible motion legs 2 are symmetrically arranged, with each group containing two legs along a 120° circumference. Two slotted round head screws 2-4 are connected to the flexible arm 2-1 through the slotted round head screw mounting holes 2-1-4 to provide the necessary stiffness for the mechanism. The capacitive displacement sensor 2-2 is fixed to the flexible arm 2-1 through the capacitive displacement sensor mounting hole 2-1-3 and is fixed via the Allen set screw mounting hole 2-1-5 to monitor the displacement of the output end of the improved SR mechanism in real time, forming a closed-loop feedback control to ensure the high-precision adjustment of the leg length. The two flexible hinges 2-1-6 are arranged vertically on the upper and lower sides of the flexible arm 2-1 to enable each flexible motion leg to achieve two-way rotational degrees of freedom.

[0021] Through the length coupling of the six flexible motion legs constructed above, the six-degree-of-freedom pose adjustment of the moving lens is realized.

[0022] Based on the principle of the SR mechanism, through offsetting the fulcrum position from the midpoint towards the output end to construct an asymmetric lever ratio, the lever reduction mechanism composed of the piezoelectric actuator and the flexible arm can achieve precise displacement regulation at the nanoscale; the capacitive displacement sensor monitors the output displacement of the mechanism in real time and forms a closed-loop feedback control, and cooperates with the coordinated adjustment of six groups of flexible motion legs to achieve six-degree-of-freedom nanoscale pose control of the lens; at the same time, the stress-free support mechanism absorbs stress through the elastic deformation of the flexible hinge, and the integrated design eliminates the assembly error, realizing the coordinated work of precise adjustment and stress-free support.

[0023] As Figure 5 shown, the stress-free support mechanism 4 includes a flexible support arm 4-1, a lens spacer 4-2, a lens pressing block 4-3, a lens hexagon socket set screw 4-4, the flexible hinge 4-5 of the flexible support arm 4-1, and the installation hole 4-6 for the stress-free support mechanism and the six-degree-of-freedom adjustment mechanism. The stress-free support mechanism 4 adopts three groups of circumferentially evenly distributed flexible support arms 4-1, and each group of support arms is provided with a specially designed flexible hinge 4-5, which can effectively absorb and eliminate the influence of assembly stress and thermal stress on the lens through elastic deformation, so as to achieve stress-free support.

[0024] Among them, the flexible support arm 4-1 realizes stress release through the elastic deformation of the flexible hinge 4-5, and the lens spacer 4-2 and the lens pressing block 4-3 cooperate with the lens hexagon socket set screw 4-4 to realize the precise positioning and fixing of the lens. Among them, the lens pressing block 4-3 provides axial binding force, the lens spacer 4-2 provides radial binding force for the lens, and the lens hexagon socket set screw 4-4 is used to fasten the lens pressing block 4-3 and the lens gasket 4-2 to ensure the accuracy of the lens installation position; the installation hole 4-6 for the stress-free support mechanism and the six-degree-of-freedom adjustment mechanism realizes the connection between the stress-free support mechanism and the six-degree-of-freedom adjustment mechanism. The overall structure adopts an integrated design to integrate the support function and the lens frame into one, and effectively eliminates the influence of assembly stress and thermal stress through the elastic deformation of the flexible hinge, realizing stress-free support and avoiding the positioning error caused by assembly of the traditional split structure.

[0025] As Figure 6 shown, the flexible arm 2-1 is improved based on the principle of the SR mechanism. Among them, point A is the output end, point B is the fixed hinge, and point C is the fulcrum. Point D is used as the input end. Under the action of the output displacement of the piezoelectric actuator 2-3, it moves to the new position D'. Point A' is the changed position corresponding to the output end point A during the process of point D moving from the initial position to D'. Compared with the traditional flexible arm, the fulcrum C position is offset from the midpoint towards the output end to form an asymmetric lever ratio, so as to achieve nanoscale displacement regulation and increase the reduction ratio while ensuring a compact structure.

[0026] In one embodiment, the base 1, the lower triangle 3, the flexible arm 2-1, and the stress-free support mechanism 4 are made of a low-expansion coefficient material such as 4J32 or 4J36.

[0027] In the specification provided herein, a number of specific details are set forth. However, it is understood that embodiments of the present invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure an understanding of this description.

[0028] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art within the technical field will appreciate that other embodiments may be contemplated within the scope of the invention as thus described. Additionally, it should be noted that the language used in this specification has been principally selected for readability and instructional purposes and not to limit or define the subject matter of the invention.

Claims

1. A compound six-degree-of-freedom stress-free support adjustment device for lenses, characterized in that: It includes a six-degree-of-freedom lens adjustment mechanism and a stress-free support mechanism (4); the six-degree-of-freedom lens adjustment mechanism is composed of a base (1), a lower triangle (3), and six flexible motion legs (2) distributed circumferentially; the stress-free support mechanism (4) is connected to the six-degree-of-freedom lens adjustment mechanism through a mounting hole (4-6) provided on the stress-free support mechanism (4).

2. The composite six-degree-of-freedom stress-free lens support and adjustment device according to claim 1, wherein: The upper part of the base (1) is connected to the projection objective support disk, and the lower part of the lower triangle (3) is connected to the stress-free support mechanism (4); six flexible motion legs (2) are arranged between the base (1) and the lower triangle (3), and axial movement of the lower triangle (3) and the stress-free support mechanism (4) along the XYZ axes and rotation around the XYZ axes are realized through the coupling of the leg lengths, so as to complete the six-degree-of-freedom pose adjustment of the lens.

3. The composite six-degree-of-freedom lens stress-free support adjustment device according to claim 2, wherein: Each flexible motion leg (2) includes a flexible arm (2-1), a piezoelectric actuator (2-3), and a capacitive displacement sensor (2-2); the piezoelectric actuator (2-3) is connected to the flexible arm (2-1) through a piezoelectric actuator mounting hole (2-1-2) provided on the flexible arm (2-1) to form an improved SR lever mechanism, and the capacitive displacement sensor (2-2) is fixed to the flexible arm (2-1) through a capacitive displacement sensor mounting hole (2-1-3) provided on the flexible arm (2-1).

4. The composite six-degree-of-freedom stress-free lens support adjustment device according to claim 3, wherein: Taking the lower ball head of the piezoelectric actuator (2-3) as the driving point, by driving the piezoelectric actuator (2-3), the internal screw rod is elongated or shortened, so that the flexible arm (2-1) undergoes relative displacement. Through the reduction conversion of the lever reduction mechanism, the total displacement is reduced, thereby completing the nanoscale adjustment of the length of the flexible motion leg (2); the capacitive displacement sensor (2-2) is used to feedback the measured high-precision displacement signal to the piezoelectric actuator (2-3), and by adjusting the displacement driving amount in real time, the high-precision control of the length of the flexible motion leg (2) is achieved.

5. The composite six-degree-of-freedom stress-free lens support and adjustment device according to claim 3, wherein: The improved SR lever mechanism includes: offsetting the fulcrum position of the flexible arm (2-1) from the midpoint to the output end, and adopting a three-group symmetric layout of the flexible motion legs (2), with each group containing two legs evenly distributed circumferentially at 120°.

6. The composite six-degree-of-freedom lens stress-free support adjustment device according to claim 4, wherein: The flexible motion leg (2) also includes a slotted cheesehead screw (2-4), a spring (2-5), and an Allen set screw (2-6). The slotted cheesehead screw (2-4) and the spring (2-5) are hooked to each other to provide pre-tightening stiffness for the flexible arm (2-1). The slotted cheesehead screw (2-4) is connected to the flexible arm (2-1) through a slotted cheesehead screw mounting hole (2-1-4), and the Allen set screw (2-6) is used to fasten the capacitive displacement sensor (2-2) to the flexible arm (2-1).

7. The composite six-degree-of-freedom stress-free lens support and adjustment device according to claim 4, characterized in that: The flexible arm (2-1) also includes two flexible hinges (2-1-6), which are located on the upper and lower sides of the flexible arm (2-1) and are used to enable each flexible motion leg (2) to achieve two-way rotational degrees of freedom.

8. The composite six-degree-of-freedom stress-free lens support adjustment device according to claim 1, characterized in that: The stress-free support mechanism (4) includes a flexible support arm (4-1), a lens pad (4-2), a lens pressing block (4-3), a lens Allen set screw (4-4), and a mounting hole (4-6); the flexible support arm (4-1) is provided with a flexible hinge (4-5).

9. The composite six-degree-of-freedom stress-free lens support and adjustment device according to claim 8, characterized in that: The fixation and positioning of the lens are achieved through the coordinated cooperation of the lens spacer block (4-2), the lens pressing block (4-3), and the lens hexagon socket set screw (4-4). The lens pressing block (4-3) provides axial restraint force, the lens spacer block (4-2) provides radial restraint force for the lens, and the lens hexagon socket set screw (4-4) is used to fasten the lens pressing block (4-3) and the lens gasket (4-2).

10. The composite six-degree-of-freedom stress-free lens support and adjustment device according to claim 3, wherein: The base (1), the lower triangle (3), the flexible arm (2-1), and the stress-free support mechanism (4) are made of a low-expansion coefficient material such as 4J32 or 4J36.

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