Magnetic field distortion resistant Halbach permanent magnet array and photoetching device

Abstract

The invention provides a Halbach permanent magnet array resistant to magnetic field distortion and a photoetching device, belongs to the technical field of photoetching machine technology and ultra-precision measurement, and solves the problems of low precision and poor stability of a photoetching machine motion platform system. The Halbach permanent magnet array comprises a plurality of array units; each array unit comprises two pieces of N-pole magnetic steel, two pieces of S-pole magnetic steel, 16 pieces of flexibly magnetized hexagonal prism magnetic steel, 24 pieces of hexagonal prism magnetic steel and 12 pieces of cuboid magnetic steel. According to the invention, a topological structure is optimally designed, a novel flexible magnetizing method is adopted, harmonic component distortion, periodic distortion and peak fluctuation distortion of an existing magnetic steel array are greatly corrected, so that the three distortion conditions are far better than those of the existing magnetic steel array, and the periodic distortion is almost completely eliminated; the fluctuation distortion dispersion degree in the non-scanning direction is greatly reduced, and the total harmonic distortion rate can be maximally corrected to one fifth before optimization.

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 field of photolithography machine technology and ultra-precision measurement technology. Background Art

[0002] The workpiece stage technology is one of the core technologies of the lithography machine. Its main feature is to achieve ultra-precision motion control with high speed and high acceleration and deceleration. In the operation process of the single workpiece stage system, the processing of silicon wafers needs to be carried out in sequence, from alignment, focusing and leveling, exposure to unloading, which will undoubtedly lead to high measurement time consumption. Integrated circuit manufacturers hope to continuously improve the productivity of lithography machines. To this end, ASML took the lead in proposing dual workpiece stage technology. The two workpiece stages can complete different steps in chip manufacturing simultaneously. During the period when one worktable is occupied for exposure, the other worktable can complete operations such as loading, alignment, focusing and leveling.

[0003] The dual-workpiece motion system needs to adopt a planar magnetic levitation permanent magnet planar motor with better performance and fewer defects. This type of motor has the characteristics of diverse structures, high thrust density, high positioning accuracy, low operating loss, and good low-speed stability. Its performance depends to a large extent on the structural design of the permanent magnet array. As the core component of the moving coil magnetic levitation motion platform, the structure of the permanent magnet array directly affects the magnetic field distribution, electromagnetic force generation, and the overall performance of the motion platform. Therefore, the structural design and optimization of the permanent magnet array of the moving coil magnetic levitation motion platform has important theoretical significance and practical application 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 will increase the complexity of the magnetic field and increase the difficulty of subsequent actuator control. 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: 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 flexibly magnetized hexagonal magnets, 24 hexagonal magnets and 12 rectangular magnets.

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

[0009] The magnetizing direction of the 12 rectangular magnets is horizontal, the magnetizing direction of the 24 hexagonal magnets is consistent with the rectangular magnets, the magnetizing direction of the 16 flexibly magnetized hexagonal magnets is 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 flexibly magnetized hexagonal magnets, the 24 hexagonal magnets and the 12 rectangular magnets are 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 row, the first column, the third column and the fifth column in the third 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 cube magnet in a horizontal magnetization direction and two flexible magnetized hexagonal magnets in horizontal magnetization directions 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 a common array unit.

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

[0014] A mask stage, used for supporting a mask;

[0015] A workbench, including a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting a 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] 1 Based on the mathematical model and simulation structure of the Halbach permanent magnet array of the moving coil magnetic levitation planar motor, the present invention proposes a new type of 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 on the dual worktable system.

[0019] 2. The present invention optimizes the topological structure and adopts a new flexible magnetization method to significantly correct the harmonic component distortion, periodic twist distortion and peak fluctuation distortion of the existing magnetic steel array, so that the three distortion conditions are far superior to the existing magnetic steel array, and the periodic distortion is almost completely eliminated, the dispersion of the fluctuation distortion in the non-scanning direction is greatly reduced, and the total harmonic distortion rate can be corrected to a maximum of one-fifth of the original value before optimization.

[0020] 3. As a new type of Halbach permanent magnet array that resists magnetic field distortion, the present invention can be used to optimize the function of the magnetic levitation wafer worktable of deep ultraviolet and extreme ultraviolet lithography equipment. The new array can be used as the stator of the moving coil magnetic levitation motion table. Compared with the commonly used magnetic steel array at this stage, it can significantly reduce the harmonic distortion while maintaining a certain air gap flux density, and at the same time reduce the other two periodic distortions and non-scanning direction peak fluctuation distortion that appear in practical applications. Thereby reducing vibration and noise, avoiding unnecessary vibration and shaking that affect position and speed control, improving the stability, response speed and control accuracy of the worktable, and achieving more precise position adjustment.

[0021] 4. Compared with the existing arrays, the Halbach array designed in the present invention generates a spatial magnetic field that is closer to the ideal mathematical model, can more effectively utilize the characteristics of the Halbach planar array, is convenient for optimizing the design of the mover motion algorithm, and achieves better performance in the system design, thereby improving the overall performance, efficiency and reliability of the magnetic levitation motion platform, which is especially important in the application of lithography machines that require high precision and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 2 A schematic diagram of the size 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 A 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 In the figure, (a) is a schematic diagram of the magnetization direction of a vertically magnetized rectangular parallelepiped magnetic steel, (b) is a schematic diagram of the magnetization direction of a horizontally magnetized rectangular parallelepiped magnetic steel, (c) is a schematic diagram of the magnetization direction of a horizontally magnetized hexagonal prism magnetic steel, and (d) is a schematic diagram of the magnetization direction of a flexibly magnetized hexagonal prism magnetic steel;

[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 a scanning direction waveform of an 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 magnetic field distortion in the non-scanning direction of an existing magnetic steel array provided by the present invention;

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

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

[0033] Fig. 9 A schematic diagram of the correction effect of the magnetic field periodic distortion of the Halbach planar permanent magnet array for resisting magnetic field distortion provided by the present invention;

[0034] Fig.10 A schematic diagram of the correction effect of the magnetic field non-scanning direction fluctuation distortion of the Halbach planar permanent magnet array resistant to magnetic field distortion provided by the present invention. DETAILED DESCRIPTION

[0035] Combination Figure 1-4 To illustrate this embodiment, 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 a plurality of array units, each array unit includes two N-level magnets, two S-level magnets, 16 flexibly magnetized hexagonal magnets, 24 hexagonal magnets in horizontal magnetization directions, and 12 cube magnets in horizontal magnetization directions.

[0036] The Halbach planar permanent magnet array that is resistant to magnetic field distortion is an array structure composed of several polygonal magnets with different heights and different 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 grade 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 grade magnets.

[0037] The hexagonal flexible magnetized magnet is used for the transition link between the N / S grade magnet and the horizontal magnetized magnet. The magnetization direction of the hexagonal flexible magnet is 45 degrees to the horizontal and N / S directions, and the magnetization amount is 1.31T. Each rectangular magnet in the horizontal magnetization direction and two hexagonal magnets in the 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.

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

[0039] like Figure 2 (b) and Figure 3 As shown, the magnetizing directions of the 12 rectangular parallelepiped magnets are all horizontal, the magnetizing directions of the 24 hexagonal prism magnets are consistent with the rectangular parallelepiped magnets, the magnetizing directions of the 16 flexibly magnetized hexagonal prism 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 flexibly magnetized hexagonal prism magnets, the 24 hexagonal prism magnets and the 12 rectangular parallelepiped magnets are all 1.31T.

[0040] As a new type of Halbach permanent magnet array resistant to magnetic field distortion, the present invention can be used to optimize the function of the magnetic levitation wafer worktable of deep ultraviolet and extreme ultraviolet lithography equipment. The new array can be used as the stator of the moving coil magnetic levitation motion table. Compared with the commonly used magnetic steel array at this stage, it can significantly reduce the harmonic distortion while maintaining a certain air gap magnetic flux density, and at the same time reduce the other two periodic distortions and non-scanning direction peak fluctuation distortion that appear in practical applications. Thereby reducing vibration and noise, avoiding unnecessary vibration and shaking that affect position and speed control, improving the stability, response speed and control accuracy of the worktable, and achieving more precise position adjustment.

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

[0042] A mask stage, used for supporting a mask;

[0043] A workbench, including a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting a 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, can more effectively utilize the characteristics of the Halbach planar array, is convenient for optimizing the design of the mover motion algorithm, and achieves better performance in system design, thereby improving the overall performance, efficiency and reliability of the magnetic levitation motion platform, which is especially important in lithography machine applications that require high precision and high stability.

[0046] Example

[0047] Combination Figure 5-10 This embodiment is described. This embodiment simulates the 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, which can be specifically divided into three types of distortion:

[0048] like Figure 5 As shown in the figure, the existing magnetic steel array has harmonic component distortion. Harmonic components exist on each magnetic field strength line, and higher harmonics are superimposed on the fundamental wave. This distortion is due to the geometric shape and natural characteristics of the permanent magnet. The harmonic components existing on each x-direction magnetic field strength line will introduce nonlinearity in the magnetic field, resulting in magnetic field distortion. Take the Bx-direction magnetic field shown in the figure below as an example. The blue dotted line is obtained by theoretical calculation, and the red solid line is the simulation result. The distorted magnetic field makes the waveform of the magnetic field no longer a complete sine wave, but contains additional frequency components, which in turn affects the stability and accuracy of the magnetic field.

[0049] like Figure 6 As shown, the existing magnetic steel array has periodic distortion. Periodic distortion refers to the periodic deformation or distortion in the magnetic field, which changes the center position of the magnetic field, which may cause the magnetic field to produce different forces or effects at different positions. As shown in the figure below, the simulation result of setting the simulation section to 5mm from the magnetic steel surface is found that the direction of the distortion is consistent with the placement of the magnetic steel, and the distortion shape and the arrangement of the small magnetic steel are both serpentine; the direction of the magnetization intensity vector of the small magnetic steel in the red circle is (-1,-1,0), and (-1,1,0) is constantly circulating, which is also the source of the X,Y field strength of the Halbach array, while the magnetization intensity direction of the large magnetic steel is perpendicular to the plane, so that the magnetic field has a height, and does not generate a lot of horizontal field strength, which has little effect on the periodic distortion. In summary, the distortion is mainly related to the arrangement structure of the small magnetic steel. It is caused by the topological structure of the permanent magnet array having a right angle and the magnetic potential concentrated on the right angle edge. In order to avoid excessive periodic distortion, it is necessary to optimize the arrangement of the small magnetic steel.

[0050] like Figure 7 (a) and Figure 7 As shown in (b), the existing magnetic steel array has peak fluctuation distortion. In addition to the periodic distortion of the magnetic field, attention is paid to the change of the peak of the magnetic field. Taking the Bx component as an example, it can be found that the peak curve has curvature in the non-scanning direction, and the period of the fluctuation is the same as the scanning magnetic field period. This peak fluctuation may be caused by the square in the array, which will cause unstable changes in the magnetic field strength, causing the extreme value of the magnetic field strength to fluctuate in space, resulting in a decrease in the uniformity of the magnetic field and an increase in asymmetry, thereby affecting the control accuracy of the magnetic levitation system.

[0051] like Figure 8-10 As shown, in this embodiment, the topological structure of the magnetic steel array is optimized and designed, and a new flexible magnetization method is adopted to significantly correct the above three distortions, so that the three distortions are far better than the prototype array, the periodic distortion is almost completely eliminated, the dispersion degree of the fluctuation distortion in the non-scanning direction is greatly reduced, and the total harmonic distortion rate can be corrected to one-fifth of the optimization value at most. 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 is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope 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-level magnets, two S-level magnets, 16 flexibly magnetized hexagonal magnets, 24 hexagonal magnets and 12 cuboid magnets.

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 size of the flexible magnetized hexagonal magnet and the hexagonal magnet are both 30mm×10mm×40mm square magnets with 5mm×5mm×40mm cut off from the four corners.

3. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: 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, the magnetizing direction of the 8 flexibly magnetized hexagonal magnets is at an angle of 45° to the N-grade magnets, the S-grade magnets and the horizontal direction, and the magnetization amounts of the 8 flexibly magnetized hexagonal magnets, the 24 hexagonal magnets and the 12 rectangular magnets are all 1.31T.

4. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: The N-level magnets, S-level magnets and rectangular magnets in each array unit are arranged in 5 rows × 5 columns, the first row, the first column, the third column and the fifth column in the third 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.

5. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: 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 which 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.

6. The Halbach permanent magnet array resistant to magnetic field distortion according to claim 1, characterized in that: Each cube magnet in a horizontal magnetization direction and two flexible magnetized hexagonal magnets in horizontal magnetization directions 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 a common array unit.

7. A lithography device, applied to a Halbach permanent magnet array resistant to magnetic field distortion as claimed in any one of claims 1 to 6, characterized in that: include: an illumination unit for providing an exposure beam; A mask stage, used for supporting a mask; A workbench, including a plurality of Halbach permanent magnet arrays resistant to magnetic field distortion, for supporting a substrate; The projection objective lens is used to transmit the pattern on the mask to the substrate in proportion.

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