CN112578639B - Limiting mechanism, mask table and photoetching machine - Google Patents

Abstract

The invention provides a limiting mechanism, a mask table and a photoetching machine, wherein a moving part is arranged on a mask table frame and can move relative to the mask table frame, the limiting mechanism is arranged on a mask cross-connecting position of the mask table frame, and a position detection module of the limiting mechanism is used for detecting whether the moving part moves to the mask cross-connecting position or not, and the limiting module of the limiting mechanism extends out to limit the moving part when the moving part is in place, so that the function of limiting the moving part when a mask plate is cross-connected is realized, and the safety when the mask plate is cross-connected is ensured.

Description

Limiting mechanism, mask table and photoetching machine

Technical Field

The invention relates to the technical field of semiconductor preparation, in particular to a limiting mechanism, a mask table and a photoetching machine.

Background

Photolithography is used primarily in the manufacture of integrated circuits, ICs, or other microdevices. A multi-layer mask having different mask patterns is sequentially imaged in precise alignment by a lithography machine onto a photoresist-coated wafer, such as a semiconductor wafer or an LCD panel. Lithography machines are largely divided into two classes, one being stepper machines, where a mask pattern is imaged in one exposure area of a wafer at a time, the wafer is then moved relative to the mask, the next exposure area is moved under the mask pattern and the projection objective, and the mask pattern is again exposed in another exposure area of the wafer, and the process is repeated until all exposure areas on the wafer have the mask pattern. Another type is a step-and-scan lithography machine, in which the mask pattern is not imaged by one exposure, but by a scanning movement of the projected light field. During mask pattern imaging, the mask and wafer are moved simultaneously relative to the projection system and the projection beam. In the above lithography machine, a corresponding device is required to be provided as a carrier for the mask plate and the silicon wafer, and the carrier loaded with the mask plate generates accurate motion to meet the lithography requirement.

In a scanning lithography machine, a mask stage is generally composed of a fine motion stage and a coarse motion stage, the fine motion stage performs fine tuning of a mask plate, and the coarse motion stage performs a large-stroke scanning exposure motion of the mask plate. With the continuous pursuit of productivity in the industry, the positioning accuracy, scanning movement speed and acceleration requirements of the mask table are continuously improved, when the mask table carries out mask plate handover, the coarse motion table of the mask table is required to move to a mask handover position, and in the handover process, the transmission manipulator can enter the mask table, so that the transmission manipulator and the mask table are required to be mechanically limited at the mask handover position in order to prevent the transmission manipulator from colliding with the mask table caused by the coarse motion under the unexpected condition.

Disclosure of Invention

The invention aims to provide a limiting mechanism, a mask table and a photoetching machine, which can limit a moving part when a mask plate is handed over, and ensure the safety of handing over the mask plate.

In order to achieve the above object, the present invention provides a position limiting mechanism, comprising:

the position detection module is used for detecting whether a moving part is in place or not;

and the limiting module extends out to limit the moving part when the moving part is in place.

Optionally, the moving part has a limiting hole, and the limiting module includes:

the limiting pin is aligned with the limiting hole after the moving part is in place;

and the driving unit is used for driving the limiting pin to extend into or withdraw from the limiting hole.

Optionally, one end of the limiting pin extending into the limiting hole is the same as the limiting hole in shape.

Optionally, the limiting hole is a waist-shaped hole, the limiting pin is an eccentric pin, and the eccentric pin is axially rotated to adjust the transverse position between the eccentric pin and the limiting hole.

Optionally, the limit module further includes a locking unit capable of rotating with the limit pin, and the locking unit includes:

the eccentric shaft sleeve is sleeved outside the limiting pin;

and the shaft sleeve seat is sleeved outside the limiting pin and locks the radial direction of the limiting pin.

Optionally, the locking unit is disposed on a fixed frame, the sleeve seat has at least two concentric virtual ring surfaces, the circle centers of the at least two virtual ring surfaces coincide with the rotation center of the limit pin, each virtual ring surface is provided with a plurality of adjusting through grooves, the fixed frame corresponding to each virtual ring surface is provided with at least one threaded hole, and when the sleeve seat is at any angle, at least one threaded hole is exposed from the adjusting through groove, so that a screw is screwed into the threaded hole to lock the radial direction of the limit pin.

Optionally, the sum of the central angles of the non-coinciding portions of all the adjustment through slots is equal to 360 degrees.

Optionally, the concentric virtual ring surface has at least one virtual diameter, the threaded hole is located at least one junction of the virtual diameter and the virtual ring surface, and on the virtual diameter, at least one threaded hole is provided on both sides of a circle center of the virtual ring surface.

Optionally, the concentric virtual ring surface has at least one pair of virtual diameters, and the threaded holes on the pair of virtual diameters are symmetrically arranged around the center of the virtual ring surface.

Optionally, the eccentricity of the limit pin is between 4mm and 6 mm.

Optionally, the driving unit includes a double-acting cylinder, the double-acting cylinder has a proximity switch, when the double-acting cylinder drives the limit pin to extend from an initial state to a maximum stroke, the proximity switch sends a first in-place signal, and when the double-acting cylinder drives the limit pin to retract to the initial state, the proximity switch sends a second in-place signal.

Optionally, an induction sheet is arranged on the moving part, when the moving part is in place, the induction sheet is aligned with the position detection module, and the position detection module detects the induction sheet to determine whether the moving part is in place.

Optionally, the position detection module comprises a proximity sensor.

Optionally, the position detection module is disposed on a mounting base, the mounting base is in threaded connection with an adjusting screw, and the adjusting screw is adjusted to adjust the transverse position of the position detection module.

Optionally, the position detection module is in threaded connection with the mounting base, and the vertical position between the position detection module and the moving part is adjusted by rotating the position detection module.

The present invention also provides a mask stage comprising:

the mask table frame is provided with a mask cross joint position;

a moving member provided on the mask stage frame and movable relative to the mask stage frame;

the limiting mechanism is arranged on a mask delivery position of the mask table frame and limits the moving component when the moving component moves to the mask delivery position.

The invention also provides a photoetching machine comprising the mask table.

In the limiting mechanism, the mask stage and the photoetching machine provided by the invention, the moving part is arranged on the mask stage frame and can move relative to the mask stage frame, the limiting mechanism is arranged on the mask delivery position of the mask stage frame, and the limiting module of the limiting mechanism is used for extending out to limit the moving part when the moving part is in place when detecting whether the moving part moves to the mask delivery position or not, so that the function of limiting the moving part when the mask plate is delivered is realized, and the safety when the mask plate is delivered is ensured.

Drawings

Fig. 1 is a perspective view of a limiting mechanism provided in an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of a limiting mechanism provided in an embodiment of the present invention along the Z direction;

fig. 3 is a schematic structural view of a waist-shaped hole as a limiting hole according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of the embodiment of the present invention in which the limiting shaft is an eccentric shaft;

fig. 5a is a schematic structural diagram of a first bearing seat according to an embodiment of the present invention;

fig. 5b is a schematic structural diagram of a second bearing seat according to an embodiment of the present invention;

FIG. 5c is a schematic structural diagram of a third bearing seat according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a fourth bearing seat according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a mask stage according to an embodiment of the present invention;

wherein the reference numerals are:

10-a housing; 11-adjusting the support; 111-a first adjustment frame; 112-a second adjustment frame; 12-a mounting seat; 13-fixing the plate; 14-a fastening screw; 15-adjusting screws; 16-a fixed frame; 20-a position detection module; 30-a limit module; 31-a drive unit; 32-a limit pin; 321-a first end of the spacing pin; 322-a second end of the spacing pin; 33-a locking unit; 331-eccentric sleeve; 332-a shaft sleeve seat; 333-virtual torus; 334-virtual diameter; 335-adjusting the through groove; 336-a threaded hole; 40-a moving part; 41-limiting holes;

1-a mask stage frame; 2-a moving part; 3-a limiting mechanism; 4-a transmission manipulator;

d1-width of the limiting hole in Y direction;

d2-width of the limiting hole in the X direction;

d3-width of the first end of the spacing pin along the Y direction;

d4-eccentricity of the limit pin;

k-the center of rotation of the spacing pin.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

For convenience of description, the present embodiment establishes an XYZ three-dimensional coordinate system with a horizontal rightward direction as a Y direction, an inward direction perpendicular to the paper surface as an X direction, and a vertical upward direction as a Z direction.

As shown in fig. 1 and fig. 2, the present embodiment provides a limiting mechanism, including:

the position detection module 20 is used for detecting whether a moving part 40 is in place;

and the limiting module 30 extends out when the moving part 40 is in place to limit the moving part 40.

In this embodiment, the limiting mechanism is disposed at a mask transfer position of a mask stage frame and is configured to limit the moving member 40 when the moving member 40 moves to the mask transfer position, and the moving member 40 is a coarse moving stage disposed on the mask stage frame and capable of moving relative to the mask stage frame.

Specifically, the moving part 40 moves along the Y direction, for example, the limiting mechanism is located below the moving part 40, and includes a housing 10, and the position detection module 20 and the limiting module 30 are both located at least partially in the housing 10. The limiting module 30 includes a driving unit 31 and a limiting pin 32 connected to the driving unit 31 (the housing 10 needs to have a hole for the limiting pin 32 to extend out or retract), in an initial state, the limiting pin 32 is located in the housing 10, the moving part 40 is provided with a limiting hole 41, when the moving part 40 is in place, the limiting hole 41 is aligned with the limiting pin 32 in the Z direction, and the driving unit 31 drives the limiting pin 32 to extend out of the housing 10 along the Z direction and extend into the limiting hole 41, so as to limit the moving part 40.

Further, a sensing piece (not shown) is disposed on the moving part 40, and when the moving part 40 is in place, the sensing piece is aligned with the detection target surface of the position detection module 20, and the position detection module 20 detects the sensing piece in real time, and once the position detection module 20 detects the sensing piece, it can determine that the moving part 40 is in place. The position detection module 20 may be a proximity sensor, and the position detection module 20 and the sensing strip need to have a standard detection distance in the Z direction (the standard detection distance of different position detection modules 20 may be different). In a long time use, when the moving component 40 is in place, the sensing piece may not be aligned with the detection target surface of the position detection module 20 (the two are deviated in the Y direction), or the distance between the position detection module 20 and the sensing piece in the Z direction is not equal to the standard detection distance (the two are deviated in the Z direction), and at this time, the Y-direction position and the Z-direction position of the position detection module 20 need to be adjusted.

In this embodiment, an adjusting bracket 11 is disposed in the housing 10, the adjusting bracket 11 has two adjusting frames, which are a first adjusting frame 111 and a second adjusting frame 112, respectively, the first adjusting frame 111 is used to fix the position detecting module 20, the second adjusting frame 112 surrounds the limit pin 32 to limit the limit pin 32, and one side of the adjusting bracket 11 is disposed on a side wall of the housing 10 to achieve fixing. Further, the position detecting module 20 is disposed on a mounting base 12, the bottom of the mounting base 12 penetrates through the first adjusting frame 111, and the width of the first adjusting frame 111 in the Y direction is greater than the width of the bottom of the mounting base 12 in the Y direction, so as to provide a moving space for the mounting base 12 in the Y direction. The bottom of the mounting seat 12 is connected with a fixing plate 13, the width of the fixing plate 13 in the X direction is greater than the width of the first adjusting frame 111 in the X direction, and the fixing plate 13 and the first adjusting frame 111 are connected by a plurality of fastening screws 14. An adjusting screw 15 is inserted through an end of the first adjusting frame 111 along the Y-direction and is screwed with the mounting base 12, when the fastening screw 14 is removed, the position of the position detecting module 20 in the Y-direction can be adjusted by adjusting the adjusting screw 15, and after the adjustment is completed, the fastening screw 14 is mounted, so that the position detecting module 20 can be fixed. Further, the position detection module 20 is screwed to the mounting base 12, and the position of the position detection module 20 in the Z direction can be adjusted by rotating the position detection module 20. In this way, when the moving part 40 is in place, the sensing piece may not be aligned with the detection target surface of the position detection module 20 and/or the distance between the position detection module 20 and the sensing piece in the Z direction is not equal to the standard detection distance, the position of the position detection module 20 may be adjusted by adjusting the adjusting screw 15 and/or rotating the position detection module 20, so as to ensure the detection accuracy of the position detection module 20.

Optionally, the adjustable stroke of the position detection module 20 in the Y direction is ± 6mm, and the adjustable stroke in the Z direction is ± 4 mm.

Further, in this embodiment, the driving unit 31 is a double-acting cylinder, the double-acting cylinder is provided with a proximity switch and a pneumatic control box solenoid valve, when the position detection module 20 detects that the moving part 40 is in place, the pneumatic control box solenoid valve acts to introduce forward air pressure into the double-acting cylinder, so that the double-acting cylinder drives the limit pin 32 to extend out from the initial state along the Z direction and extend into the limit hole 41 of the moving part 40, after the limit pin 32 extends out to the maximum stroke (extends into the limit hole 41 to the maximum extent), which indicates that the limit action is completed, the proximity switch sends a first in-place signal, at this time, a mask plate handover action can be performed, after the mask plate handover is completed, the pneumatic control box solenoid valve acts to introduce reverse air pressure into the double-acting cylinder, so that the double-acting cylinder drives the limit pin 32 to retract from the initial state along the-Z direction, when the limit pin 32 reaches the initial state, the proximity switch sends a second in-position signal, and the moving part 40 can leave the connection position, so that the condition that the limit pin 32 and the moving part 40 collide with each other can be avoided.

Optionally, the shape of the end of the limit pin 32 extending into the limit hole 41 is the same as that of the limit hole 41, for example, the end of the limit pin 32 extending into the limit hole 41 and the limit hole 41 are both circular or square, and the widths of the limit hole 41 in the Y direction and the X direction may be slightly larger than the widths of the limit pin 32 in the Y direction and the X direction, so that the limit pin 32 can extend into the limit hole 41. Because the position of the mask table is referred to by the whole frame, and the position of the limiting mechanism is also referred to by the whole frame, when the mask table is used for a long time, the position of the moving part 40 relative to the mask connecting position has errors including errors of size, servo and the like, and when the moving part 40 is in place, the limiting hole 41 can not be aligned with the limiting pin 32 (the two have deviation in the Y direction), so that the limiting pin 32 can not accurately extend into the limiting hole 41. In order to eliminate the error and realize the adjustable mask connection position, as shown in fig. 3, the limiting hole 41 may be a kidney-shaped hole, and the width D1 in the Y direction is larger than the width D2 in the X direction. As shown in fig. 3 and 4, the limit pin 32 is an eccentric pin, that is, the axes of the two outer circles of the limit pin 32 are not overlapped to form an eccentric structure. For convenience of description, one end of the limit pin 32 extending into the limit hole 41 is referred to as a first end 321, and one end of the limit pin 32 extending into the limit hole 41 is referred to as a second end 322, in this embodiment, a width D3 of the first end 321 along the Y direction is, for example, 25mm to 35mm, and an eccentricity D4 (a distance between axes of two outer circles) of the limit pin 32 is between 4mm to 6mm, so that when the limit pin 32 rotates, there may be an adjustment margin of ± D4 in the Y direction, and a width D1 of the kidney-shaped hole in the Y direction needs to be greater than a sum of a width D3 and two times D4 of the first end 321 along the Y direction, so as to ensure that an adjustment stroke of the limit pin 32 in the Y direction does not exceed a range of the limit hole 41.

Further, as shown in fig. 3, a hexagonal inner hole is formed in the rotation center K of the stopper pin 32, and the stopper pin 32 can rotate around the rotation center K by inserting an inner hexagonal wrench into the inner hole. In order to ensure that the eccentric pin can be locked in the Y direction when rotating at any angle, as shown in fig. 1 and 2, the limiting module 30 further includes a locking unit 33 capable of rotating along with the limiting pin 32, the locking unit 33 includes an eccentric shaft sleeve 331 and a shaft sleeve seat 332, the eccentric shaft sleeve 331 is sleeved on the first end 321 of the limiting pin 32 and can rotate along with the limiting pin 32, and the limiting pin 32 can move along the Z direction relative to the eccentric shaft sleeve 331, so that the limiting pin 32 can extend out of the housing 10. The shaft sleeve seat 332 is disc-shaped and sleeved on the eccentric shaft sleeve 331, and can rotate along with the eccentric shaft sleeve 331, that is, when the limit pin 32 rotates, the eccentric shaft sleeve 331 and the shaft sleeve seat 332 rotate synchronously.

The eccentric shaft sleeve 331 is located above a fixed frame 16, and the fixed frame 16 plays a role in carrying and fixing the eccentric shaft sleeve 331. As shown in fig. 5a to 6, the shaft sleeve seat 332 has at least two concentric virtual ring surfaces 333, the center of the virtual ring surfaces 333 coincides with the rotation center of the limit pin 32, each virtual ring surface 333 is provided with a plurality of adjusting through slots 335, each adjusting through slot 335 extends along the edge of the virtual ring surface 333, the sum of the central angles of the non-coinciding portions of all the adjusting through slots 335 is equal to 360 degrees, that is, all the adjusting through slots 335 at least need to enclose a circle, each fixed frame 16 corresponding to each virtual ring surface 333 is provided with at least one threaded hole 336, the threaded holes 336 are matched with the adjusting through grooves 335, so that at least one threaded hole 336 is exposed out of the adjusting through groove 335 when the shaft sleeve seat 332 is at any angle, so as to lock the Y-direction of the stopper pin 32 by screwing a screw into the screw hole 336.

Further, in order to ensure that at least one of the threaded holes 336 is exposed from the adjusting through slot 335 when the shaft sleeve seat 332 is at any angle, the position of the threaded hole 336 needs to be specially designed. The concentric virtual ring surface 333 has at least one virtual diameter 334, the threaded hole 336 is located at least one intersection of the virtual diameter 334 and the virtual ring surface 333, and the virtual diameter 334 is divided into a first portion and a second portion by a circle center of the virtual ring surface 333, and the threaded hole 336 is disposed on each of the first portion and the second portion.

The present embodiment is exemplified by two concentric virtual ring surfaces 333 on the shaft sleeve seat 332, all the adjusting through slots 335 enclosing a circle. As shown in fig. 5a, the sleeve seat 332 has two virtual ring surfaces 333, and each of the two virtual ring surfaces 333 is a semi-circle, so that the two virtual ring surfaces 333 just enclose a whole circle. A virtual diameter 334 is drawn on the virtual ring surface 333 (since the two virtual ring surfaces 333 are concentric, the virtual diameters 334 of the two virtual ring surfaces 333 are coincident), the virtual diameter 334 and each virtual ring surface 333 have two junctions, which are respectively located on the first part and the second part of the virtual diameter 334, the threaded hole 336 of each virtual ring surface 333 is located on the fixed frame 16 corresponding to the junction, but the threaded holes 336 of the two virtual ring surfaces 333 cannot be located on one side of the rotation center K, and when each virtual ring surface 333 corresponds to only one threaded hole 336, the threaded holes 336 corresponding to the two virtual ring surfaces 333 are located on both sides of the rotation center K. Further, each virtual ring surface 333 and the virtual face change have two junctions, and the two junctions can be correspondingly provided with one threaded hole 336, so that the two threaded holes 336 are exposed from the adjusting through groove 335 when the shaft sleeve seat 332 is at any angle, and the locking effect can be improved.

As shown in fig. 5b and 5c, the two concentric virtual rings 333 may further have two virtual diameters 334, the two virtual diameters 334 are symmetrical along the X direction, as mentioned above, each virtual diameter 334 has two intersections with each virtual annulus 333, as shown in figure 5b, one threaded hole 336 may be correspondingly formed at any intersection of each of the virtual ring surfaces 333, as long as two threaded holes 336 are respectively ensured at both sides of the rotation center K, alternatively, as shown in fig. 5c, one threaded hole 336 may be provided at each intersection of the virtual annulus 333, when the shaft sleeve seat 332 is at any angle, the four threaded holes 336 are exposed out of the adjusting through groove 335, the locking capacity is stronger, and the shaft sleeve seat 332 is symmetrical in structure, so that the stability can be improved.

Further, as shown in fig. 6, the adjusting through slots 335 on each virtual ring surface 333 may also be not semicircular, but quarter circular arcs, each virtual ring surface 333 has two symmetrically arranged adjusting through slots 335 of the quarter circular arcs, and the positions of the four adjusting through slots 335 are complementary, so that the four adjusting through slots 335 just enclose a whole circle. One threaded hole 336 is formed at each intersection of the virtual ring surfaces 333, so that four threaded holes 336 are exposed from the adjusting through groove 335 when the shaft sleeve seat 332 is at any angle. It can be understood that the distribution of the adjusting through slots 335 on each virtual ring surface 333 may be varied as long as the total of the central angles of the non-overlapping portions of all the adjusting through slots 335 is ensured to be equal to 360 degrees, the virtual diameter 334 on each virtual ring surface 333 may be one, two, three, four, and the like, the present invention is not limited thereto, and the threaded hole 336 may be correspondingly provided only at one junction of two junctions of each virtual diameter 334 and each virtual ring surface 333, and the threaded holes 336 may also be correspondingly provided at both junctions, as long as the threaded holes 336 are ensured to be provided at both sides of the rotation center K on any virtual diameter 334.

Based on this, as shown in fig. 7, the present embodiment also provides a mask stage including:

the mask table frame 1 can be fixed on a supporting surface and is provided with a mask connecting position;

a moving part 2, which is arranged on the mask stage frame 1 and can move relative to the mask stage frame 1, optionally, the moving part 2 is a coarse moving stage moving along the Y direction, the coarse moving stage bears a mask plate, and when the coarse moving stage moves to the mask transfer position along the Y direction, the mask transfer can be performed;

and the limiting mechanism 3 is arranged on a mask delivery position of the mask table frame 1 and limits the moving part 2 when the moving part 2 moves to the mask delivery position, so that a transmission manipulator 4 for delivering a mask plate is prevented from colliding with the coarse moving table when the mask plate is delivered.

Further, the embodiment also provides a lithography machine comprising the mask table.

In summary, in the limiting mechanism, the mask stage and the lithography machine provided in the embodiments of the present invention, the moving component is disposed on the mask stage frame and is capable of moving relative to the mask stage frame, the limiting mechanism is disposed on the mask transfer position of the mask stage frame, and the position detection module of the limiting mechanism is configured to detect whether the moving component moves to the mask transfer position, and when the moving component is in place, the limiting module of the limiting mechanism extends out to limit the moving component, so that a function of limiting the moving component when a mask plate is transferred is realized, and safety when the mask plate is transferred is ensured.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (14)

1. A stop gear, its characterized in that includes:

the position detection module is used for detecting whether a moving part is in place or not;

the limiting module is used for limiting the moving part when the moving part is in place;

the motion part is provided with a limiting hole, and the limiting module comprises:

the limiting pin is aligned with the limiting hole after the moving part is in place;

the driving unit is used for driving the limiting pin to extend into or withdraw from the limiting hole;

spacing module still includes can follow the rotatory locking unit of spacer pin, the locking unit includes:

the eccentric shaft sleeve is sleeved outside the limiting pin;

the shaft sleeve seat is sleeved outside the limiting pin and locks the radial direction of the limiting pin;

the locking unit is arranged on a fixed frame, the shaft sleeve seat is provided with at least two concentric virtual ring surfaces, the circle centers of the at least two virtual ring surfaces are overlapped with the rotation center of the limiting pin, each virtual ring surface is provided with a plurality of adjusting through grooves, the fixed frame corresponding to each virtual ring surface is provided with at least one threaded hole, and when the shaft sleeve seat is at any angle, at least one threaded hole is exposed out of the adjusting through groove so as to lock the radial direction of the limiting pin by screwing a screw into the threaded hole.

2. The spacing mechanism of claim 1, wherein the end of the spacing pin extending into the spacing hole is the same shape as the spacing hole.

3. The spacing mechanism of claim 1, wherein said spacing hole is a kidney-shaped hole, said spacing pin is an eccentric pin, and the lateral position between said eccentric pin and said spacing hole is adjusted by axially rotating said eccentric pin.

4. The spacing mechanism of claim 1, wherein the sum of the central angles of the non-coincident portions of all of said adjustment channels is equal to 360 degrees.

5. The spacing mechanism as claimed in claim 4, wherein said concentric virtual torus has at least one virtual diameter, said threaded hole is located at least one intersection of said virtual diameter and said virtual torus, and at least one said threaded hole is located on each side of said virtual diameter from a center of said virtual torus.

6. The spacing mechanism as claimed in claim 5, wherein said concentric virtual annulus has at least one pair of virtual diameters, and the threaded holes on said pair of virtual diameters are symmetrically disposed about the center of said virtual annulus.

7. A spacing mechanism as claimed in claim 3, wherein the eccentricity of the spacing pin is between 4mm and 6 mm.

8. The spacing mechanism of claim 1, wherein said drive unit comprises a double acting cylinder having a proximity switch that signals a first in-position when said double acting cylinder drives said spacing pin to extend from an initial state to a maximum travel, and a second in-position when said double acting cylinder drives said spacing pin to retract to said initial state.

9. The limiting mechanism according to claim 1, wherein a sensing piece is arranged on the moving part, when the moving part is in place, the sensing piece is aligned with the position detection module, and the position detection module detects the sensing piece to judge whether the moving part is in place.

10. A spacing mechanism as claimed in claim 1 or 9, wherein said position detection module comprises a proximity sensor.

11. The limiting mechanism according to claim 1 or 9, wherein the position detection module is disposed on a mounting seat, the mounting seat is in threaded connection with an adjusting screw, and the adjusting screw is adjusted to adjust the transverse position of the position detection module.

12. The spacing mechanism as claimed in claim 11, wherein said position detection module is threadedly coupled to said mounting base, and wherein vertical position between said position detection module and said moving member is adjusted by rotating said position detection module.

13. A mask stage, comprising:

the mask table frame is provided with a mask cross joint position;

a moving member provided on the mask stage frame and movable relative to the mask stage frame;

the spacing mechanism of any of claims 1-12, disposed on a mask interface of the mask table frame and configured to space the moving component when the moving component moves to the mask interface.

14. A lithographic apparatus comprising the mask table of claim 13.

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