A fixing device, equipment and method for a long strip mirror of a dual-frequency laser interferometer

Abstract

This invention provides a device, equipment, and method for fixing a long strip mirror in a dual-frequency laser interferometer. Addressing the dynamic deformation problem caused by fixing both ends of a long strip mirror in ultra-precision motion platform equipment, a rigid container is used. Dynamic compensation is achieved through the stiffness of an air film and the pressure difference: when the slide accelerates, the bending tendency of the long strip mirror increases the air pressure inside the container, generating a counterforce to suppress deformation; when stationary or moving at a constant speed, the air pressure decreases, and the external atmospheric pressure provides support. This method eliminates the need for intermediate mechanical fixing points, avoids over-constraint problems, and combines high precision with ease of installation. It is suitable for ultra-precision motion platforms in fields such as semiconductor manufacturing and precision testing.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing equipment, and particularly relates to a method, apparatus and equipment for fixing a long strip mirror of a dual-frequency laser interferometer. Background Technology

[0002] In the semiconductor manufacturing field, the wafer stage positioning accuracy of a lithography machine directly determines the limits of chip feature sizes. Laser interferometers and grating interferometers, as two core positioning technologies, have significantly different technical approaches that impact equipment performance. Laser interferometers, using a helium-neon laser wavelength (approximately 633 nm) as a reference, achieve nanometer-level positioning by measuring the phase difference between two-frequency lasers. This offers the advantage of being traceable to the International System of Units (SI) and is widely used in ultra-precision equipment such as extreme ultraviolet (EUV) and deep ultraviolet (DUV) lithography machines. However, the fixing method of the core component of this technology—the elongated reflector—still faces the dual challenges of dynamic stability and installation accuracy.

[0003] Currently, the elongated reflectors (typically over 300 mm in length) of dual-frequency laser interferometers generally employ a three-point support structure with rigid clamping at both ends and a suspended middle. This design is advantageous during acceleration and deceleration of the motion table (acceleration can reach...). The above will lead to the following problems: Uneven bending moment distribution: The fixed points at both ends of the long mirror bear the main load, and the bending moment is concentrated in the middle area due to the suspension, resulting in micron-level flexural deformation of the mirror surface; Dynamic response lag: Traditional fixing methods cannot compensate for deformation in real time, resulting in a phase difference between the displacement signal measured by the interferometer and the actual movement, which is eventually converted into positioning error.

[0004] Traditional solutions still have significant limitations: 1. Using epoxy resin or other adhesives to completely bond the bottom surface of the long mirror to the base results in approximately 1-3% volume shrinkage during the adhesive curing process, leading to residual stress on the mirror surface and affecting initial installation accuracy. Furthermore, the Young's modulus of the adhesive (E ≈ 2-4 GPa) is much lower than that of glass (E ≈ 70 GPa), making it prone to creep deformation under long-term thermal cycling. 2. Adding a mechanical support point (such as a ball-head plunger) in the middle of the long mirror can reduce flexural deformation, but it introduces over-constraint problems: Degree of freedom conflict: The length change of the long mirror due to thermal expansion is restricted by the mechanical support point, leading to thermal stress. 3. Nonlinear contact stiffness: The contact stiffness of the mechanical support point does not match the stiffness of the long mirror itself, easily causing high-frequency vibration amplification effects. Summary of the Invention

[0005] Therefore, it is necessary to provide a fixing device, equipment, and method for the long strip mirror of a dual-frequency laser interferometer to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a fixing device for a long strip mirror of a dual-frequency laser interferometer, characterized in that it includes:

[0007] A long, narrow mirror, with sliding platforms supporting both ends;

[0008] At least one rigid container is fixed to the slide and located on one or both sides of the suspended area in the middle of the long mirror;

[0009] A pressure damping cavity is formed between the elongated mirror and the rigid container; the spacing of the pressure damping cavity is 5-10 micrometers.

[0010] In one embodiment, the surface of the rigid container is distributed with interconnected micropores, and the internal pores are interconnected.

[0011] In one embodiment, the rigid container includes a horizontal container and a vertical container, located in the horizontal and vertical suspended areas of the long mirror, respectively.

[0012] In one embodiment, the rigid container is made of ceramic, metal, or composite material.

[0013] In one embodiment, the ceramic is alumina, silicon nitride, or zirconium oxide;

[0014] In one embodiment, the metal is sintered stainless steel or aluminum alloy;

[0015] In one embodiment, the composite material is carbon fiber reinforced silicon carbide.

[0016] In one embodiment, the rigid container has a micropore size of 20-100 micrometers and a porosity of 30%-60%.

[0017] In one embodiment, the air film stiffness of the pneumatic damping cavity is .

[0018] In one embodiment, the rigid container is fixed to the slide by adhesive bonding, welding or mechanical fastening.

[0019] Secondly, this application also provides an ultra-precision motion platform device, characterized in that it includes:

[0020] XY motion slide;

[0021] Dual-frequency laser interferometer system;

[0022] In the above embodiment, the elongated mirror fixing device uses the elongated mirror to reflect laser light to determine the position of the sliding table.

[0023] Thirdly, this application also provides a method for fixing a long strip mirror in a dual-frequency laser interferometer, characterized by comprising the following steps:

[0024] Fix both ends of the long mirror to the sliding table;

[0025] A rigid container is set in the suspended area in the middle of the long mirror to form a pneumatic damping cavity with a spacing of 5-10 micrometers;

[0026] The pressure difference in the pneumatic damping cavity is used to dynamically suppress the deformation of the long mirror during acceleration and deceleration of the slide.

[0027] The aforementioned fixing device, equipment, and method for the long strip mirror of a dual-frequency laser interferometer utilizes an elastic damping device added to the middle of the long strip mirror. This device, composed of the long strip mirror and a rigid container, achieves dynamic compensation through the stiffness of the air film and the air pressure difference: when the slide accelerates, the bending tendency of the long strip mirror increases the air pressure inside the container, generating a counterforce to suppress deformation; when stationary or moving at a constant speed, the air pressure decreases, and the external atmospheric pressure provides support. Bidirectional dynamic stability is achieved through a dual-container structure in both horizontal and vertical directions. This method eliminates the need for intermediate mechanical fixing points, avoiding over-constraint problems, and combines high precision with ease of installation, making it suitable for ultra-precision motion platforms in fields such as semiconductor manufacturing and precision testing. The core innovation lies in the integrated design of the air pressure damping device and the long strip mirror, effectively resolving the contradiction between dynamic deformation and installation complexity in traditional methods. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the long strip mirror fixing device for a dual-frequency laser interferometer in one embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the long strip mirror fixing device for a dual-frequency laser interferometer in one embodiment of the present invention;

[0031] Figure 3 This is a layout diagram of the air pressure damping cavity in the suspended area of ​​the fixed structure in one embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram illustrating the principle of long strip mirror deformation and air pressure compensation during slide acceleration in one embodiment of the present invention;

[0033] Figure 5 This is an enlarged schematic diagram of the microporous structure in one embodiment of the present invention.

[0034] exist Figures 1 to 5 middle,

[0035] 1: Sliding table; 2: Long mirror; 3: Horizontal rigid container; 4: Vertical rigid container; 5 & 6: Fixture; 7: Laser. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This application provides an embodiment of a long strip mirror fixing device for a dual-frequency laser interferometer, such as... Figure 1-2 As shown, the device includes:

[0038] The long mirror 2 is supported at both ends by the sliding table 1;

[0039] At least one rigid container 3 or 4 is fixed on the slide table 1 and located on one or both sides of the suspended area in the middle of the long mirror 2;

[0040] The elongated mirror 2 and the rigid containers 3 and 4 form a pneumatic damping cavity with a spacing of 5-10 micrometers;

[0041] The rigid containers 3 and 4 have interconnected micropores distributed on their surfaces, with a pore size of 20-100 micrometers, and the internal pores are interconnected.

[0042] refer to Figure 4 As shown, the dynamic compensation mechanism of the fixing device is as follows: Since there is no support in the middle, the force at both ends of the long mirror is greater than that in the middle, causing the middle part to bend as shown in the figure. When this tendency occurs, the long mirror is equivalent to pressurizing the alumina ceramic container. At the same time, the increased pressure inside the pressure container will give the long mirror a reaction force, suppressing this deformation tendency. Similarly, when the acceleration is opposite to the direction shown in the figure, the deformation tendency is also opposite to that shown in the figure. The long mirror tends to move away from the horizontal pressure container. The pressure inside the pressure container will be less than the atmospheric pressure. At this time, the external atmospheric pressure will give the long mirror a force, suppressing the tendency of the long mirror to move away from the pressure container. The principle of action in the height direction is similar. The two directions work together to ensure the stability of the middle part of the long mirror on the sliding table.

[0043] The elongated mirror 2 can be made of glass, quartz, or sapphire with a surface roughness Ra≤10nm to ensure high reflection accuracy and low scattering loss. The two ends of the elongated mirror are fixed to the XY slide 1 by fixing seats 5 and 6. This fixing method ensures the stability of the elongated mirror and avoids excessive constraint on the elongated mirror body, preventing stress from deteriorating the optical performance.

[0044] In one embodiment, the rigid containers 3 and 4 can be selected as alumina ceramic containers. (Purity 99.6%) An alumina ceramic container is placed in both the horizontal and vertical directions. The surface micropores have a diameter of 20-100 micrometers and a porosity of 30%-60%. These micropores are formed into an array-connected structure through laser micromachining, allowing the internal pores of the container to communicate with each other, forming a pressure-damping cavity. This cavity can store some air while ensuring the system's sensitivity to pressure changes. Figure 5 As shown. This microporous design and manufacturing process enable the pneumatic damping cavity to dynamically suppress the deformation of the long mirror by real-time changes in air pressure difference during the acceleration and deceleration of the slide table.

[0045] The pneumatic damping cavity has a 5-10 μm gap between the elongated mirror and the container, forming a nearly sealed air film with a stiffness of [missing information]. The stiffness value is achieved through precise control of the spacing and micro-hole parameters, ensuring sufficient support while maintaining the flexibility of the elongated mirror's movement. When the sliding table is at a constant speed or with minimal acceleration / deceleration, the elongated mirror will not deform and affect the system's accuracy when suspended. Preferably, the spacing between the elongated mirror and the container is set to 6 μm.

[0046] Optionally, such as Figure 3 As shown, the rigid containers 3 and 4 include a horizontal container 3 and a vertical container 4, which are located in the horizontal and vertical suspended areas of the long mirror 2, respectively, forming horizontal and vertical air pressure damping cavities.

[0047] Optionally, the rigid container is made of ceramic, metal, or composite material.

[0048] Furthermore, the ceramic is alumina, silicon nitride, or zirconium oxide;

[0049] The metal is sintered stainless steel or aluminum alloy;

[0050] The composite material is carbon fiber reinforced silicon carbide.

[0051] Those skilled in the art will understand that the above examples are merely examples of materials or structures for conventional rigid containers. The core function of these rigid containers is to achieve dynamic compensation of pressure differences through a microporous structure, such as... Figure 5As shown, those skilled in the art can balance performance, cost, and environmental adaptability by reasonably selecting alternative materials.

[0052] The rigid containers 3 and 4 are fixed to the slide table 1 by adhesive, welding or mechanical fastening.

[0053] Those skilled in the art will understand that the structure shown in the figure is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the device to which the present application is applied. The specific device may include more or fewer components than shown in the figure, or combine certain components, or have different component arrangements.

[0054] In one embodiment, an ultra-precision motion platform device is also provided, comprising:

[0055] XY motion slide;

[0056] Dual-frequency laser interferometer system;

[0057] In the above embodiment, the elongated mirror fixing device uses the elongated mirror to reflect laser light to determine the position of the sliding table.

[0058] In one embodiment, a method for fixing a long strip mirror in a dual-frequency laser interferometer is also provided, comprising the following steps:

[0059] Fix both ends of the long mirror to the sliding table;

[0060] A rigid container is set in the suspended area in the middle of the long mirror to form a pneumatic damping cavity with a spacing of 5-10 micrometers;

[0061] The pressure difference in the pneumatic damping cavity is used to dynamically suppress the deformation of the long mirror during acceleration and deceleration of the slide.

[0062] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention.

Claims

1. A device for fixing a long strip mirror in a dual-frequency laser interferometer, characterized in that, include: A long, narrow mirror, with sliding platforms supporting both ends; The elongated mirror is made of quartz or sapphire with a surface roughness Ra≤10nm; At least one rigid container is fixed to the slide and located on one or both sides of the suspended area in the middle of the long mirror; A pneumatic damping cavity is formed between the elongated mirror and the rigid container. The spacing between the pneumatic damping cavities is 5-10 micrometers, and the air film stiffness of the pneumatic damping cavity is [missing information]. ; The rigid container has interconnected micropores on its surface, and the internal pores are interconnected, which can store some air. The dynamic compensation mechanism of the fixing device allows the long mirror to pressurize or depressurize the pressure vessel formed by the rigid container and the air pressure damping cavity when the middle part of the long mirror tends to bend. The pressure inside the pressure vessel increases or decreases, giving the long mirror a reaction force to suppress the bending tendency and ensure that the middle part of the long mirror is stable on the slide.

2. The apparatus according to claim 1, characterized in that: The rigid container includes a horizontal container and a vertical container, located in the horizontal and vertical suspended areas of the long mirror, respectively.

3. The apparatus according to claim 1, characterized in that: The rigid container is made of ceramic, metal, or composite material.

4. The apparatus according to claim 3, characterized in that: The ceramic is alumina, silicon nitride, zirconium oxide, or silicon carbide; The metal is sintered stainless steel or aluminum alloy; The composite material is carbon fiber reinforced silicon carbide.

5. The apparatus according to claim 1, characterized in that: The rigid container has a micropore diameter of 50 micrometers and a porosity of 30%-60%.

6. The apparatus according to claim 1, characterized in that: The rigid container is fixed to the slide by adhesive, welding or mechanical fastening.

7. An ultra-precision motion platform device, characterized in that, include: XY motion slide; Dual-frequency laser interferometer system; The elongated mirror fixing device according to any one of claims 1-6, wherein the elongated mirror reflects a laser to determine the position of the slide.

8. A method for fixing a long strip mirror in a dual-frequency laser interferometer, characterized in that, Includes the following steps: Fix both ends of the long mirror to the sliding table; The elongated mirror is made of quartz or sapphire with a surface roughness Ra≤10nm; A rigid container is disposed in the suspended region in the middle of the elongated mirror to form a pneumatic damping cavity with a spacing of 5-10 micrometers. The air film stiffness of the pneumatic damping cavity is... ; The pressure difference in the pneumatic damping cavity is used to dynamically suppress the deformation of the long mirror during acceleration and deceleration of the slide table; The rigid container has interconnected micropores on its surface, and the internal pores are interconnected, which can store some air. When the middle part of the elongated mirror has a bending tendency, the elongated mirror will pressurize or depressurize the pressure vessel formed by the rigid container and the air pressure damping cavity. The pressure inside the pressure vessel increases or decreases, giving the elongated mirror a reaction force to suppress the bending tendency and ensure that the middle part of the elongated mirror is stable on the slide.

Images