An open plane static pressure air floating turntable with high rotation accuracy

Abstract

An open-type plane static pressure air-floating turntable with high rotational precision belongs to the field of ultra-precision processing equipment. The specific scheme is as follows: An open-type plane static pressure air-floating turntable with high rotational precision includes a spindle rotor, a sleeve and a base. The sleeve is fixed on the base. The spindle rotor includes a platform and a hemispherical structure arranged in the middle of the lower surface of the platform. A groove I for accommodating the hemispherical structure is arranged in the middle of the upper surface of the sleeve. The hemispherical structure and the groove I form a hemispherical bearing. The upper surface of the sleeve and the lower surface of the platform form a thrust bearing, thereby forming an open air-floating bearing structure. In combination with the surface throttling form, the overall structure of the invention is simple, the processing and manufacturing are convenient, and it is easy to achieve higher precision. A certain preload is applied to the air-floating bearing by adjusting the gravity of the spindle rotor and its load and adjusting the vacuum degree in the vacuum air path, so that the two bearing surfaces can achieve an optimal stiffness and load matching under the condition of appropriate air film gap, and have good robustness.

Description

Technical Field

[0001] The invention belongs to the field of ultra-precision machining equipment, and in particular relates to an open-type plane static pressure air-floating turntable with high rotation accuracy. Background Art

[0002] The photolithography machine is a major equipment in the field of ultra-precision manufacturing. It is mainly used for the photolithography process in the chip processing process, that is, scanning and exposing the chip wafer and etching the integrated circuit on it. Due to the high precision required in chip manufacturing, higher requirements are placed on the accuracy of wafer scanning and detection. As an important component of the photolithography machine air floating workbench, the plane static pressure air floating bearing has been used in wafer scanning and detection, and has received widespread attention from the industry in recent years. According to the next step of the development of photolithography technology, the next generation of photolithography technology will use extreme ultraviolet lithography (EUVL) technology. Since EUVL technology is only applicable to high vacuum environments, the plane static pressure air floating bearing is required to meet the requirements of high vacuum working environment.

[0003] The existing planar static pressure air bearings used in lithography machines cannot meet the requirements of working in a high vacuum environment due to their structural characteristics. Therefore, in order to meet the needs of the development of lithography technology, it has become an urgent problem to design a planar static pressure air bearing turntable that can work in a high vacuum environment and has high rigidity and high rotation accuracy. Summary of the invention

[0004] In order to meet the needs of a flat static pressure air floating turntable working in a vacuum environment and improving its rotation accuracy, the present invention provides an open flat static pressure air floating turntable with high rotation accuracy.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An open plane static pressure air floating turntable with high rotation accuracy comprises a main shaft rotor, a shaft sleeve and a base, wherein the shaft sleeve is fixed on the base, the main shaft rotor comprises a platform and a hemispherical structure arranged in the middle of the lower surface of the platform, a groove I for accommodating the hemispherical structure is arranged in the middle of the upper surface of the shaft sleeve, the bottom of the hemispherical structure is connected to a rotor driving device and is driven to rotate by the rotor driving device, a hemispherical bearing is formed between the hemispherical structure and the groove I, a thrust bearing is formed between the upper surface of the shaft sleeve and the lower surface of the platform, an annular air channel I is arranged at the junction of the thrust bearing and the hemispherical bearing, the annular air channel I is connected to an air supply source, an annular air channel II is arranged on the thrust bearing, and the annular air channel II and the bottom of the hemispherical bearing are both connected to a vacuum pump.

[0007] Compared with the prior art, the present invention has the following beneficial effects:

[0008] Compared with the traditional flat static pressure air floating turntable, the present invention adopts an open structure with surface throttling, and cooperates with hemispherical bearings to make the overall structure simple, the number of parts is greatly reduced, the structure of each part is simple, the processing and manufacturing are convenient, and it is easy to achieve high precision.

[0009] The present invention designs a set of vacuum air paths so that the gas overflowing from the thrust air film and the hemispherical air film can be promptly evacuated without leaking into the external vacuum environment, thereby meeting the requirements for working in a high vacuum environment.

[0010] Since the present invention is an open static pressure air bearing structure, the bearing can be preloaded by adjusting the gravity of the main shaft rotor and its load and the vacuum degree in the vacuum air circuit, so that the two bearing surfaces can achieve an optimal stiffness and load-bearing match when the air film gap is appropriate, so that it has high stiffness and good robustness.

[0011] Due to the use of a hemispherical bearing structure, it has the performance of automatic self-aligning and can easily achieve high rotation accuracy. Combined with a thrust bearing on one side and a surface throttling structure, it can have greater load-bearing characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is an axial cross-sectional view of the air supply path of the present invention;

[0013] Figure 2 It is an axial cross-sectional view of the vacuum air path of the present invention;

[0014] Figure 3 It is a schematic diagram of the three-dimensional structure of the present invention;

[0015] Figure 4 A schematic diagram of the gas flow direction on the bearing surface of the present invention;

[0016] Figure 5 It is a top view of the gas flow direction of the bearing surface of the present invention.

[0017] In the figure, 1, spindle rotor, 2, sleeve, 3, base, 4, rotor drive device, 5, annular air channel I, 6, annular air channel II, 7, air supply path, 8, base cover, 9, harness box, 10, data connector, 11, platform, 12, hemispherical structure, 21, groove I, 22, axial air channel III, 23, pore I, 24, pore II, 25, vacuum adapter, 31, chamber, 41, mover mounting shaft, 42, motor mover, 43, motor stator, 44, mover pressure plate, 45, stator pressure plate, 46, reading head mounting seat, 47, reading head, 48, circular grating, 49, grating mounting shaft, 71, oblique air channel I, 72, axial air channel I, 73, axial air channel II, 74, radial air channel I, 75, air supply adapter. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Specific implementation method 1

[0020] An open-type plane static pressure air-floating turntable with high rotation accuracy comprises a spindle rotor 1, a sleeve 2 and a base 3, wherein the sleeve 2 is arranged at the lower part of the spindle rotor 1, and the bottom of the sleeve 2 is fixedly connected to the base 3 by bolts, and the spindle rotor 1 comprises a platform 11 and a hemispherical structure 12 arranged in the middle of the lower surface of the platform 11, and a groove Ⅰ21 for accommodating the hemispherical structure 12 is arranged in the middle of the upper surface of the sleeve 2, and the bottom of the hemispherical structure 12 is connected to a rotor driving device 4 and driven by the rotor driving device 4. The hemispherical structure 12 and the groove Ⅰ21 form a hemispherical bearing, the upper surface of the sleeve 2 (not at the groove Ⅰ21) and the lower surface of the platform 11 (not at the hemispherical structure 12) form a thrust bearing, and an open static pressure air bearing structure is formed as a whole. An annular air channel Ⅰ5 is provided at the junction of the thrust bearing and the hemispherical bearing, and the annular air channel Ⅰ5 is connected to the air supply source. An annular air channel Ⅱ6 is provided on the thrust bearing, and the annular air channel Ⅱ6 and the bottom of the hemispherical bearing are both connected to the vacuum pump. After the air supply source supplies air to the annular air channel Ⅰ5, the gas passes from the annular air channel Ⅰ5 to the hemispherical bearing and the thrust bearing, forming a surface throttling structure, thereby forming an air film, so that the spindle rotor 1 and its load float. The open-type plane static pressure air-floating turntable with high rotation accuracy described in the present invention works in a vacuum environment. The gas coming out of the air film surface of the thrust bearing is gathered in the annular air passage II6 and pumped out by a vacuum pump, and the gas coming out of the air film surface of the hemispherical bearing is pumped out at the bottom by a vacuum pump. The present invention adjusts the preload force by its own gravity and the vacuum degree of the vacuum air passage to achieve high rigidity. In addition, due to the use of surface throttling and the structural form of the hemispherical bearing, it has the advantages of simple processing and manufacturing and easy to achieve high rotation accuracy.

[0021] Furthermore, the upper surface of the platform 11 is provided with a plurality of threaded holes for equipping other accessories.

[0022] Furthermore, a chamfer is provided at the top circumference of the groove Ⅰ21, and an annular air channel Ⅰ5 is formed between the hemispherical structure 12 and the chamfer; or, an annular groove Ⅱ is provided at the junction of the hemispherical structure 12 and the lower surface of the platform 11, and an annular air channel Ⅰ5 is formed between the sleeve 2 and the groove Ⅱ; or, a chamfer is provided at the top circumference of the groove Ⅰ21, and an annular groove Ⅱ is provided at the junction of the hemispherical structure 12 and the lower surface of the platform 11, and an annular air channel Ⅰ5 is formed between the chamfer and the groove Ⅱ.

[0023] Further, the lower surface of the platform 11 is circumferentially provided with a groove III, and an annular air channel II6 is formed between the groove III and the upper surface of the sleeve 2; or, the upper surface of the sleeve 2 is circumferentially provided with a groove IV, and an annular air channel II6 is formed between the groove IV and the lower surface of the platform 11; or, the lower surface of the platform 11 is circumferentially provided with a groove III, and the upper surface of the sleeve 2 is circumferentially provided with a groove IV, and the groove III and the groove IV are correspondingly arranged to form an annular air channel II6.

[0024] Furthermore, the annular air channel I5 is connected to the air supply source through two sets of symmetrically arranged air supply paths 7, and the air supply path 7 includes an oblique air channel I71 and an axial air channel I72 arranged on the sleeve 2, and an axial air channel II73 and a radial air channel I74 arranged on the base 3. The upper end of the oblique air channel I71 is connected to the annular air channel I5, and the lower end is connected to the upper end of the corresponding axial air channel I72, the lower end of the axial air channel I72 is connected to the upper end of the corresponding axial air channel II73, the lower end of the axial air channel II73 is connected to one end of the corresponding radial air channel I74, and the other end of the radial air channel I74 leads to the outside of the base 3 and is connected to the air supply source through the air supply adapter 75.

[0025] Furthermore, two axial air channels III22 are symmetrically arranged on the sleeve 2, the upper ends of the two axial air channels III22 are connected to the annular air channel II6, and the lower ends are connected to the gap I23 between the sleeve 2 and the base 3, the bottom of the hemispherical bearing is connected to the gap I23 through the gap II24 between the sleeve 2 and the rotor drive device 4, and the gap I23 is connected to the vacuum pump.

[0026] Furthermore, the open plane static pressure air flotation turntable further comprises a base cover plate 8, the base 3 is provided with a chamber 31 for accommodating the rotor drive device 4, the base cover plate 8 is fixed to the bottom of the base 3 by bolts, and is used to close the lower part of the open plane air flotation turntable, so that the chamber 23 is in a closed state, and the pores I 23 and the vacuum pump are both connected to the chamber 23. The axial airway III 22, pores I 23, pores II 24 and the chamber together constitute a vacuum air path, and the base 3 is provided with a vacuum adapter 25, one end of the vacuum adapter 25 is connected to the chamber, and the other end is connected to the vacuum pump.

[0027] Furthermore, the rotor driving device 4 includes a mover mounting shaft 41, a motor mover 42 and a motor stator 43. The middle part of the sleeve 2 is provided with a through hole 24 connected to the groove Ⅰ21. The mover mounting shaft 41 is sleeved inside the through hole 24. The bottom of the hemispherical structure 12 is fixedly connected to the top of the mover mounting shaft 41 by bolts. The motor mover 42 is installed at the bottom of the outer wall of the mover mounting shaft 41 to provide torque for the spindle rotor 1. The motor stator 43 is rotatably connected to the motor mover 42. The motor stator 43 is fixedly arranged in the stator accommodating groove of the base 3. The central axis of the motor stator 43 coincides with the central axis of the spindle rotor 1.

[0028] Furthermore, the motor mover 42 and the motor stator 43 are frameless torque motors.

[0029] Furthermore, the rotor driving device also includes a mover pressure plate 44 and a stator pressure plate 45. The mover pressure plate 44 is arranged at the bottom of the electronic mover 42 and the mover mounting shaft 41 and is fixedly connected to the mover mounting shaft 41, and is used to press the motor mover 42 so that the motor mover 42 and the mover mounting shaft 41 remain in a fixed state. The stator pressure plate 45 is arranged at the bottom of the motor stator 43 and is fixedly connected to the base 3, and is used to press the motor stator 43 so that the motor stator 43 and the base 3 remain in a fixed state.

[0030] Furthermore, the rotor drive device 4 also includes a read head mounting seat 46, a read head 47, a circular grating 48 and a grating mounting shaft 49, the read head 47 is mounted on the read head mounting seat 46, the read head mounting seat 46 is fixed on the base 3, the circular grating 48 is mounted on the grating mounting shaft 49, the grating mounting shaft 49 is fixed on the mover pressure plate 44 and then fixed on the mover mounting shaft 41, the read head 47 and the circular grating 48 are arranged correspondingly to provide spindle position and speed feedback.

[0031] Furthermore, the open plane static pressure air floating turntable also includes a harness box 9 and a data connector 10, wherein the harness box 9 is mounted on the side wall of the base 3 for fixing the data connector 10, and the data connector 10 is mounted on the harness box 9. The harness is used to connect the motor stator 43 and the wiring harness on the reading head 47.

[0032] The open plane static pressure air-floating turntable with high rotational accuracy can apply a certain preload to the thrust bearing and the hemispherical bearing by adjusting the gravity of the spindle rotor 1 and its load and adjusting the vacuum degree in the vacuum air circuit, so that the two bearing surfaces can achieve an optimal match between stiffness and load when the air film gap is appropriate, so that it has high stiffness and good robustness.

[0033] The open plane static pressure air floating turntable with high rotation accuracy adopts an open structure and surface throttling, which makes the overall structure simple, and each component is easy to be processed and manufactured, and it is easy to achieve higher precision; it adopts a half ball bearing structure with automatic self-aligning performance, which is easy to achieve high rotation accuracy, and is combined with a thrust bearing on one side and a surface throttling structure, so that it has greater load-bearing characteristics.

[0034] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An open-type plane static pressure air-floating turntable with high rotation accuracy, comprising a main shaft rotor (1), a shaft sleeve (2) and a base (3), wherein the shaft sleeve (2) is fixed on the base (3), and is characterized in that: The spindle rotor (1) comprises a platform (11) and a hemispherical structure (12) arranged in the middle of the lower surface of the platform (11); a groove I (21) for accommodating the hemispherical structure (12) is arranged in the middle of the upper surface of the shaft sleeve (2); the bottom of the hemispherical structure (12) is connected to the rotor driving device (4) and is driven to rotate by the rotor driving device (4); a hemispherical bearing is formed between the hemispherical structure (12) and the groove I (21); a thrust bearing is formed between the upper surface of the shaft sleeve (2) and the lower surface of the platform (11); an annular air channel I (5) is arranged at the junction of the thrust bearing and the hemispherical bearing; the annular air channel I (5) is connected to an air supply source; an annular air channel II (6) is arranged on the thrust bearing; the annular air channel II (6) and the bottom of the hemispherical bearing are both connected to a vacuum pump; Two axial air passages III (22) are symmetrically arranged on the shaft sleeve (2), the upper ends of the two axial air passages III (22) are both connected to the annular air passage II (6), and the lower ends are both connected to the pore I (23) between the shaft sleeve (2) and the base (3), the bottom of the hemispherical bearing is connected to the pore I (23) through the pore II (24) between the shaft sleeve (2) and the rotor drive device (4), and the pore I (23) is connected to the vacuum pump.

2. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1 is characterized in that: The top circumference of the groove I (21) is chamfered, and an annular air channel I is formed between the hemispherical structure (12) and the chamfer. (5); or, an annular groove II is provided at the junction of the hemispherical structure (12) and the lower surface of the platform (11), and an annular air channel I (5) is formed between the sleeve (2) and the groove II; or, a chamfer is provided at the top circumference of the groove I (21), and an annular groove II is provided at the junction of the hemispherical structure (12) and the lower surface of the platform (11), and an annular air channel I (5) is formed between the chamfer and the groove II.

3. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1 is characterized in that: The lower surface of the platform (11) is circumferentially provided with a groove III, and an annular air channel II (6) is formed between the groove III and the upper surface of the sleeve (2); or, the upper surface of the sleeve (2) is circumferentially provided with a groove IV, and an annular air channel II (6) is formed between the groove IV and the lower surface of the platform (11); or, the lower surface of the platform (11) is circumferentially provided with a groove III, and the upper surface of the sleeve (2) is circumferentially provided with a groove IV, and the groove III and the groove IV are correspondingly arranged to form an annular air channel II (6).

4. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1 or 2, characterized in that: The annular air channel I (5) is connected to the air supply source through two sets of symmetrically arranged air supply paths (7), and the air supply path (7) includes an oblique air channel I (71) and an axial air channel I (72) arranged on the sleeve (2), and an axial air channel II (73) and a radial air channel I (74) arranged on the base (3). The upper end of the oblique air channel I (71) is connected to the annular air channel I (5), and the lower end is connected to the upper end of the corresponding axial air channel I (72). The lower end of the axial air channel I (72) is connected to the upper end of the corresponding axial air channel II (73). The lower end of the axial air channel II (73) is connected to one end of the corresponding radial air channel I (74), and the other end of the radial air channel I (74) is connected to the air supply source.

5. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1, characterized in that: The open plane static pressure air floating turntable also includes a base cover (8), and a chamber (31) for accommodating a rotor driving device (4) is provided on the base (3). The base cover (8) is fixed to the bottom of the base (3) so that the chamber (31) is in a closed state, and the pore I (23) and the vacuum pump are both connected to the chamber (31).

6. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1, characterized in that: The rotor driving device (4) comprises a rotor mounting shaft (41), a motor rotor (42) and a motor stator (43); a through hole communicating with the groove I (21) is provided in the middle of the shaft sleeve (2); the rotor mounting shaft (41) is sleeved inside the through hole; the bottom of the hemispherical structure (12) is fixedly connected to the top of the rotor mounting shaft (41); the motor rotor (42) is mounted on the bottom of the outer wall of the rotor mounting shaft (41); the motor rotor (42) is rotatably connected to the motor stator (43); the motor stator (43) is fixed on the base (3); and the central axis of the motor stator (43) coincides with the central axis of the spindle rotor (1).

7. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 6, characterized in that: The rotor drive device further comprises a mover pressure plate (44) and a stator pressure plate (45); the mover pressure plate (44) is fixedly connected to the bottom of the mover mounting shaft (41) and is used to press the motor mover (42) so that the motor mover (42) and the mover mounting shaft (41) are kept in a fixed state; the stator pressure plate (45) is fixedly connected to the base (3) and is used to press the motor stator (43) so that the motor stator (43) and the base (3) are kept in a fixed state.

8. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 7, characterized in that: The rotor drive device (4) further comprises a reading head mounting seat (46), a reading head (47), a circular grating (48) and a grating mounting shaft (49); the reading head (47) is mounted on the reading head mounting seat (46); the reading head mounting seat (46) is fixed on the base (3); the circular grating (48) is mounted on the grating mounting shaft (49); the grating mounting shaft (49) is fixed on the mover mounting shaft (41); and the reading head (47) and the circular grating (48) are arranged correspondingly.

9. The open-type plane static pressure air-floating turntable with high rotation accuracy according to claim 1, characterized in that: The open-type plane static pressure air-floating turntable further comprises a wiring harness box (9) and a data connector (10); the wiring harness box (9) is mounted on the base (3), and the data connector (10) is mounted on the wiring harness box (9).

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