A Halbach permanent magnet array and lithography device resistant to magnetic field distortion

Abstract

The present invention proposes a Halbach permanent magnet array and lithography device that are resistant to magnetic field distortion. These devices belong to the fields of lithography machine technology and ultra-precision measurement technology, and address the low precision and poor stability of lithography machine motion stage systems. The Halbach permanent magnet array comprises several array units, each of which includes two N-grade magnets, two S-grade magnets, 16 flexibly magnetized hexagonal magnets, 24 hexagonal magnets, and 12 rectangular parallelepiped magnets. By optimizing the design topology and employing a novel flexible magnetization method, the present invention significantly corrects the harmonic component distortion, periodic twist distortion, and peak fluctuation distortion of existing magnet arrays, resulting in far superior distortions in all three categories. Periodic distortion is almost completely eliminated, and the dispersion of fluctuation distortion in the non-scanning direction is significantly reduced, with the total harmonic distortion rate corrected to a maximum of one-fifth of the optimized value.

Description

Technical Field

[0001] The invention relates to a Halbach permanent magnet array and a photolithography device resistant to magnetic field distortion, belonging to the fields of photolithography machine technology and ultra-precision measurement technology. Background Art

[0002] Worktable technology is one of the core technologies of photolithography machines. Its main feature is ultra-precision motion control with high speed and high acceleration and deceleration. In the operation process of a single-stage system, silicon wafers must be processed sequentially, from loading and alignment, focusing and leveling, exposure, to unloading, which undoubtedly leads to high measurement time consumption. Integrated circuit manufacturers hope to continuously improve the productivity of photolithography machines. To this end, ASML pioneered dual-stage technology. Two worktables can simultaneously complete different steps in chip manufacturing. While one worktable is occupied for exposure, the other worktable can complete operations such as loading, alignment, focusing and leveling.

[0003] Dual-workpiece motion systems require planar magnetic levitation permanent magnet motors (PMMs) with superior performance and fewer drawbacks. These motors offer diverse structural features, high thrust density, high positioning accuracy, low operating losses, and excellent low-speed stability. Their performance depends largely on the structural design of the permanent magnet array. As the core component of a moving-coil maglev motion platform, the structure of the permanent magnet array directly influences magnetic field distribution, electromagnetic force generation, and the overall performance of the platform. Therefore, structural design and optimization of the permanent magnet array of a moving-coil maglev motion platform is of great theoretical and practical value.

[0004] At present, most Halbach permanent magnet arrays adopt the structure proposed by Frissen et al., which has a higher air gap flux density and reduces the space occupied by non-ferromagnetic media such as air. However, the excited spatial magnetic field has very obvious magnetic field distortion, including harmonic component distortion, periodic distortion and non-scanning direction peak distortion. These distortions increase the complexity of the magnetic field and make subsequent actuator control more difficult. Summary of the Invention

[0005] The present invention aims to solve the problems of low precision and poor stability of a moving stage system of a photolithography machine, and further proposes a Halbach permanent magnet array and a photolithography device that are resistant to magnetic field distortion.

[0006] The technical solution adopted by the present invention to solve the above problems is as follows: the present invention proposes a Halbach permanent magnet array resistant to magnetic field distortion, comprising a plurality of array units;

[0007] Each array unit includes two N-grade magnets, two S-grade magnets, 16 flexible magnetized hexagonal magnets, 24 hexagonal magnets and 12 rectangular magnets.

[0008] The size of the rectangular parallelepiped magnet is 20mm×20mm×40mm. The flexible magnetized hexagonal magnet and the hexagonal magnet are both 30mm×10mm×40mm square magnets with 5mm×5mm×40mm cut off from their four corners.

[0009] The magnetizing direction of the 12 rectangular magnets is horizontal, the magnetizing direction of the 24 hexagonal magnets is consistent with that of the rectangular magnets, and the magnetizing direction of the 16 flexible magnetized hexagonal magnets is at an angle of 45° to the N-grade magnets, S-grade magnets and the horizontal direction. The magnetizing capacity of the 16 flexible magnetized hexagonal magnets, the 24 hexagonal magnets and the 12 rectangular magnets is all 1.31T.

[0010] The N-level magnets, S-level magnets and rectangular magnets in each array unit are arranged in 5 rows × 5 columns. The first column, third column and fifth column in the first row, third row and fifth row are all gaps. The second column in the second row is the first N-level magnet, the second column in the fourth row is the first S-level magnet, the fourth column in the second row is the second S-level magnet, the fourth column in the fourth row is the second N-level magnet, and the rest are rectangular magnets.

[0011] The 16 flexibly magnetized hexagonal magnets and the 24 hexagonal magnets are all arranged around the first N-level magnet, the second N-level magnet, the first S-level magnet, the second S-level magnet and the rectangular magnet. Among them, the flexibly magnetized hexagonal magnets are arranged around the first N-level magnet, the second N-level magnet, the first S-level magnet and the second S-level magnet, and the rest are hexagonal magnets.

[0012] Each horizontally magnetized cube magnet and two horizontally magnetized flexible hexagonal magnets are arranged in the same magnetization direction to form a special-shaped magnet unit. Each array unit has 8 special-shaped magnet units connected to other array units.

[0013] A photolithography apparatus comprises: an illumination unit for providing an exposure beam;

[0014] A mask stage, used to support the mask;

[0015] A workbench, comprising a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting the substrate;

[0016] The projection objective lens is used to transmit the pattern on the mask to the substrate in proportion.

[0017] The beneficial effects of the present invention are:

[0018] Based on the mathematical model and simulation structure of the Halbach permanent magnet array of a moving-coil magnetic levitation planar motor, this paper proposes a novel Halbach permanent magnet array that is resistant to magnetic field distortion by rationally designing the structure of the permanent magnet array. This successfully reduces the interference of magnetic field distortion on motion and improves the efficiency of electromagnetic force generation, which has far-reaching significance for promoting the in-depth research of dual-workpiece table systems.

[0019] 2. The present invention significantly improves the harmonic component distortion, periodic twist distortion, and peak fluctuation distortion of existing magnetic steel arrays by optimizing the design topology and adopting a new flexible magnetization method. All three distortion conditions are far superior to those of existing magnetic steel arrays. In addition, periodic distortion is almost completely eliminated, and the dispersion of fluctuation distortion in the non-scanning direction is greatly reduced. The total harmonic distortion rate can be corrected to a maximum of one-fifth of the original value before optimization.

[0020] 3. This invention, a novel Halbach permanent magnet array resistant to magnetic field distortion, can be used to optimize the magnetic levitation wafer worktable function of deep ultraviolet and extreme ultraviolet lithography equipment. This new array can serve as the stator of a moving-coil magnetic levitation motion stage. Compared to currently used magnetic steel arrays, this array significantly reduces harmonic distortion while maintaining a certain air gap flux density. It also reduces two other types of periodic distortion and non-scanning direction peak fluctuation distortion that occur in practical applications. This reduces vibration and noise, prevents unnecessary vibration and shaking from affecting position and speed control, improves the worktable's stability, response speed, and control accuracy, and enables more precise position adjustment.

[0021] 4. Compared with existing arrays, the Halbach array designed in this invention generates a spatial magnetic field that is closer to the ideal mathematical model. It can more effectively utilize the characteristics of the Halbach planar array, facilitate the optimization of the mover motion algorithm design, and achieve better performance in system design, thereby improving the overall performance, efficiency and reliability of the magnetic levitation motion stage, which is especially important in applications such as lithography machines that require high precision and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a Halbach permanent magnet array resistant to magnetic field distortion provided by the present invention;

[0023] Figure 2 A schematic diagram of the dimensions and magnetization direction of a Halbach permanent magnet array resistant to magnetic field distortion provided by the present invention;

[0024] Figure 2 In the figure, (a) is a schematic diagram of the dimensions of a Halbach permanent magnet array and a photolithography device that are resistant to magnetic field distortion, and (b) is a schematic diagram of the magnetization direction of a Halbach permanent magnet array and a photolithography device that are resistant to magnetic field distortion;

[0025] Figure 3 Schematic diagram of the magnetization direction of the flexible magnetized hexagonal magnetic steel, hexagonal magnetic steel and rectangular parallelepiped magnetic steel provided by the present invention;

[0026] Figure 3 Among them, (a) is a schematic diagram of the magnetization direction of the vertically magnetized rectangular parallelepiped magnet, (b) is a schematic diagram of the magnetization direction of the horizontally magnetized rectangular parallelepiped magnet, (c) is a schematic diagram of the magnetization direction of the horizontally magnetized hexagonal prism magnet, and (d) is a schematic diagram of the magnetization direction of the flexibly magnetized hexagonal prism magnet;

[0027] Figure 4 A physical picture of a Halbach permanent magnet array that is resistant to magnetic field distortion provided by the present invention;

[0028] Figure 5 A schematic diagram of the scanning direction waveform of the existing magnetic steel array provided by the present invention;

[0029] Figure 6 A schematic diagram of the periodic distortion of the top of the Bx component magnetic field of the existing magnetic steel array provided by the present invention;

[0030] Figure 7 A schematic diagram of the magnetic field distortion in the non-scanning direction of the existing magnetic steel array provided by the present invention;

[0031] Figure 7 In the figure, (a) is a schematic diagram of the magnetic field distortion in the non-scanning direction under ideal conditions, and (b) is a schematic diagram of the magnetic field distortion in the non-scanning direction under actual conditions;

[0032] Figure 8 A schematic diagram showing a comparison between the magnetic field waveform simulation and theoretical analysis of the Halbach planar permanent magnet array resistant to magnetic field distortion provided by the present invention;

[0033] Figure 9 A schematic diagram of the correction effect of the magnetic field periodic distortion of the Halbach planar permanent magnet array with anti-magnetic field distortion provided by the present invention;

[0034] Figure 10 This is a schematic diagram of the correction effect of the magnetic field non-scanning direction fluctuation distortion of the Halbach planar permanent magnet array with anti-magnetic field distortion provided by the present invention. DETAILED DESCRIPTION

[0035] Combine Figure 1-4 This embodiment is described as follows. Figure 1 and Figure 4 As shown, the structure of a Halbach permanent magnet array that is resistant to magnetic field distortion described in this embodiment includes several array units, each array unit includes two N-level magnets, two S-level magnets, 16 flexibly magnetized hexagonal magnets, 24 hexagonal magnets with horizontal magnetization directions, and 12 cube magnets with horizontal magnetization directions.

[0036] The Halbach planar permanent magnet array, which is resistant to magnetic field distortion, consists of an array structure composed of several polygonal magnets with different heights and magnetization directions. When calculating the mathematical model, it can be regarded as the superposition of two layers of Halbach arrays in the vertical direction. In this array, the N / S-level magnets magnetized along the same vertical direction are distributed along the diagonal, and the magnets in other magnetization directions can be regarded as distributed around the N / S-level magnets.

[0037] Hexagonal flexible magnetized magnets are used as transition links between N / S grade magnets and horizontal magnetized magnets. The magnetizing direction of the hexagonal flexible magnetized magnets is 45 degrees to both the horizontal and N / S directions, and the magnetizing capacity is 1.31T. Each horizontally magnetized rectangular magnet and two horizontally magnetized hexagonal magnets are arranged in the same magnetizing direction to form a special-shaped magnet unit. Each array unit has 8 special-shaped magnet units connected to other array units.

[0038] like Figure 2 As shown in (a), the size of the rectangular magnet is 20mm×20mm×40mm, the flexible magnetized hexagonal magnet and the hexagonal magnet are both 30mm×10mm×40mm square magnets with 5mm×5mm×40mm cut off from their four corners.

[0039] like Figure 2 (b) and Figure 3 As shown, the magnetizing directions of the 12 rectangular magnets are all horizontal, the magnetizing directions of the 24 hexagonal magnets are consistent with the rectangular magnets, the magnetizing directions of the 16 flexible magnetized hexagonal magnets are at an angle of 45° to the N-grade magnets, the S-grade magnets and the horizontal direction, and the magnetizing amounts of the 16 flexible magnetized hexagonal magnets, the 24 hexagonal magnets and the 12 rectangular magnets are all 1.31T.

[0040] As a novel, magnetic field-distortion-resistant Halbach permanent magnet array, this invention can be used to optimize the magnetic levitation wafer worktable function of deep ultraviolet and extreme ultraviolet lithography equipment. This new array can serve as the stator of a moving-coil magnetic levitation motion stage. Compared with currently used magnetic steel arrays, it can significantly reduce harmonic distortion while maintaining a certain air gap flux density. It also reduces two other types of periodic distortion and non-scanning direction peak fluctuation distortion that occur in practical applications. This reduces vibration and noise, prevents unnecessary vibration and shaking from affecting position and speed control, improves the stability, response speed, and control accuracy of the worktable, and enables more precise position adjustment.

[0041] A photolithography apparatus comprises: an illumination unit for providing an exposure beam;

[0042] A mask stage, used to support the mask;

[0043] A workbench, comprising a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting the substrate;

[0044] The projection objective lens is used to transmit the pattern on the mask to the substrate in proportion.

[0045] Compared with existing arrays, the Halbach array designed in the present invention generates a spatial magnetic field that is closer to the ideal mathematical model. It can more effectively utilize the characteristics of the Halbach planar array, facilitate the optimization of the mover motion algorithm design, and achieve better performance in system design, thereby improving the overall performance, efficiency and reliability of the magnetic levitation motion table, which is especially important in applications of lithography machines that require high precision and high stability.

[0046] Example

[0047] Combine Figure 5-10 This embodiment is described. This embodiment simulates an existing magnetic steel array. Comprehensive simulation results show that the actual magnetic field of the existing magnetic steel array is significantly different from the theoretical magnetic field. Specifically, there are three types of distortion:

[0048] like Figure 5 As shown, existing magnetic steel arrays exhibit harmonic distortion. Harmonic components exist on every magnetic field intensity line, with higher harmonics superimposed on the fundamental wave. This distortion is due to the geometry and natural characteristics of the permanent magnets. The harmonic components present on every x-direction magnetic field intensity line introduce nonlinearity into the magnetic field, causing magnetic field distortion. For example, the Bx-direction magnetic field shown in the figure below shows the theoretically calculated blue dashed line and the simulated red solid line. This distorted magnetic field causes the magnetic field waveform to no longer be a perfect sine wave, but instead include additional frequency components, which in turn affects the stability and accuracy of the magnetic field.

[0049] like Figure 6 As shown, existing magnet arrays exhibit periodic distortion. Periodic distortion refers to periodic deformation or distortion in a magnetic field, causing the center of the magnetic field to shift, potentially resulting in different forces or effects at different locations. The figure below shows the simulation results, with the simulation cross section set to 5mm from the magnet surface. The direction of the distortion is consistent with the placement of the magnets, and the distortion shape and the arrangement of the small magnets are both serpentine. The magnetization vector direction of the small magnet in the red circle is (-1, -1, 0), which continuously cycles through (-1, 1, 0), which is also the source of the X and Y field strength of the Halbach array. The magnetization direction of the large magnet is perpendicular to the plane, giving the magnetic field a high degree of height and not generating much horizontal field strength, thus having little impact on the periodic distortion. In summary, this distortion is primarily related to the arrangement of the small magnets. This is due to the right-angled topology of the permanent magnet array, which results in the magnetic potential being concentrated at the right-angle edges. To avoid excessive periodic distortion, the arrangement of the small magnets needs to be optimized.

[0050] like Figure 7 (a) and Figure 7 As shown in (b), existing magnet arrays exhibit peak fluctuation distortion. Besides the periodic distortion of the magnetic field, the peak variation of the magnetic field, taking the Bx component as an example, reveals that the peak curve exhibits curvature in the non-scanning direction, and the period of the fluctuation is the same as the scanning magnetic field period. This peak fluctuation can be caused by the square shape in the array, which can cause unstable changes in magnetic field intensity. This causes spatial fluctuations in the magnetic field intensity extremes, resulting in reduced magnetic field uniformity and increased asymmetry, thus affecting the control accuracy of the maglev system.

[0051] like Figure 8-10 As shown, this embodiment optimizes the topological structure of the magnetic steel array and adopts a new flexible magnetization method to significantly correct the three types of distortion mentioned above, making all three types of distortion far better than the prototype array. The periodic distortion is almost completely eliminated, the dispersion of the non-scanning direction fluctuation distortion is greatly reduced, and the total harmonic distortion rate can be corrected to a maximum of one-fifth of the original value. The simulation results of the existing magnetic steel array and the Halbach planar permanent magnet array with anti-magnetic field distortion when the air gap height is 5mm are shown in Table 1.

[0052] Table 1

[0053]

[0054] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A Halbach permanent magnet array resistant to magnetic field distortion, characterized in that: The structure of the Halbach permanent magnet array resistant to magnetic field distortion comprises: a plurality of array units; Each array unit includes two N-grade magnetic steels, two S-grade magnetic steels, 16 flexible magnetized hexagonal magnetic steels, 24 other hexagonal magnetic steels and 12 rectangular parallelepiped magnetic steels; The magnetization direction of the 12 rectangular parallelepiped magnetic steels is all horizontal, the magnetization direction of the 24 other hexagonal prism magnetic steels is consistent with that of the rectangular parallelepiped magnetic steels, the magnetization direction of the 16 flexible magnetized hexagonal prism magnetic steels forms an angle of 45° with the N-grade magnetic steel, the S-grade magnetic steel, and the horizontal direction, and the magnetization amount of the 16 flexible magnetized hexagonal prism magnetic steels, the 24 other hexagonal prism magnetic steels, and the 12 rectangular parallelepiped magnetic steels is all 1.31T; The N-grade magnetic steel, S-grade magnetic steel and rectangular parallelepiped magnetic steel in each array unit are arranged in 5 rows × 5 columns, the first column, third column and fifth column of the first row, third row and fifth row are all gaps, the second column of the second row is the first N-grade magnet, the second column of the fourth row is the first S-grade magnet, the fourth column of the second row is the second S-grade magnet, the fourth column of the fourth row is the second N-grade magnet, and the rest are rectangular parallelepiped magnetic steel; The 16 flexibly magnetized hexagonal magnets and the 24 another type of hexagonal magnets are all arranged around the first N-level magnet, the second N-level magnet, the first S-level magnet, the second S-level magnet and the rectangular magnet. Among them, the flexibly magnetized hexagonal magnets are arranged around the first N-level magnet, the second N-level magnet, the first S-level magnet and the second S-level magnet, and the rest are another type of hexagonal magnet.

2. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: The size of the rectangular parallelepiped magnet is 20mm×20mm×40mm, and the flexible magnetized hexagonal magnet and another hexagonal magnet are both 30mm×10mm×40mm square magnets with 5mm×5mm×40mm cut off from their four corners.

3. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: Each rectangular parallelepiped magnet in a horizontal magnetization direction and two flexible magnetized hexagonal magnets in a horizontal magnetization direction are arranged in the same magnetization direction to form a special-shaped magnet unit. Each array unit has 8 special-shaped magnet units connected to other array units.

4. A lithography device, applied to a Halbach permanent magnet array resistant to magnetic field distortion according to any one of claims 1 to 3, characterized in that: include: an illumination unit for providing an exposure beam; A mask stage, used to support the mask; A workbench, comprising a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting the substrate; The projection objective lens is used to transmit the pattern on the mask to the substrate in proportion.

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