A lithography machine grating measurement calibration system

Abstract

The application provides a photolithography machine grating measurement calibration system and relates to the technical field of grating measurement. The application discloses a photolithography machine grating measurement calibration system, which relates to the technical field of grating measurement and comprises a rack, a motion system with independent motion directions, a plane grating assembly, a grating reading head assembly, a laser interferometer assembly, a following motion system, a vacuum bellows assembly and a mirror assembly. The vacuum bellows is installed on the following motion system and located between the corresponding laser interferometer and the mirror. The following system is fixed on the rack and moves along with the motion system. The grating reading head assembly and the plane grating assembly are respectively fixed on the X direction and the Y direction of the motion system. The grating reading head and the plane grating cooperate with each other and feed back the linear displacement of the calibrated object in the X direction and the Y direction and the rotation angles around the X axis, the Y axis and the Z axis in real time. The linear displacement and the rotation angles of the calibrated object (the mirror assembly and the plane grating assembly) measured by the grating reading head and the laser interferometer are compared, and the calibration is completed.

Description

Technical Field

[0001] This invention relates to the field of grating measurement technology, and in particular to a grating measurement and calibration system for a lithography machine. Background Technology

[0002] Laser interferometers and grating interferometers are widely used in ultra-precision machining and measurement. Laser interferometers use the laser wavelength as the measurement reference, while two-degree-of-freedom grating interferometers use the grating pitch and the laser wavelength as the measurement reference. In a grating interferometer measurement system, the displacement along the grating lines is a function of the grating pitch. Therefore, the grating pitch calibration method typically involves designing a structure based on the measurement principles of both laser and grating interferometers, and then comparing the measurement parameters of both to complete the grating calibration.

[0003] In existing technologies, laser interferometers are used to calibrate the grating pitch. However, when the laser interferometer and the object being calibrated are both in a standard atmospheric environment, the air significantly interferes with the refractive index of the laser signal from the interferometer, resulting in a marked decrease in the measurement accuracy of the laser interferometer and consequently affecting the calibration accuracy. To avoid the influence of air on the refractive index of the light wavelength, existing technologies typically use a very large vacuum cavity to completely cover the laser interferometry system. This approach is not only complex to operate and difficult to maintain, but also costly.

[0004] Furthermore, in existing technologies, planar grating calibration platforms for calibrating grating pitch typically have two motion axes superimposed (the movement of one motion axis drives the other). This requires that the length of the mirror used with the laser interferometer on one motion axis must be greater than the stroke of the other motion axis. In this approach, the mirror and laser interferometer will move relative to each other along a direction perpendicular to the laser path during measurement, thus requiring a large mirror. A large mirror not only requires very high installation accuracy, but vibrations during movement can also negatively impact measurement accuracy.

[0005] Solving the above problems has become the focus of efforts for those skilled in the art. Summary of the Invention

[0006] To address the technical challenges of existing planar grating calibration platforms for grating pitch calibration, such as the high installation accuracy required for large-sized reflectors and the impact of vibration during movement on measurement accuracy, this invention proposes a grating measurement and calibration system for lithography machines.

[0007] The technical solution to the technical problem is as follows:

[0008] A lithography machine grating measurement and calibration system includes a frame, a motion system with at least two degrees of freedom whose motion directions are independent of each other, a planar grating assembly, a grating reading head assembly, and a follower motion system that is linked to the motion system.

[0009] The planar grating assembly and the grating reading head assembly are respectively mounted on a single degree-of-freedom component of the motion system. Each degree-of-freedom component with the planar grating assembly mounted and the degree-of-freedom component with the grating reading head assembly mounted are equipped with a reflector, and the mirror surface of each reflector is perpendicular to the motion direction of its corresponding degree-of-freedom component.

[0010] The frame is equipped with a laser interferometer that mates with each reflector; a vacuum bellows is installed between the corresponding laser interferometer and the reflector, and the vacuum bellows is installed on the following motion system and moves synchronously with the motion system.

[0011] In one embodiment, the motion system is a two-degree-of-freedom motion system mounted on a frame, and the two-degree-of-freedom components are two motion system movers with opposite and perpendicular motion directions. The planar grating assembly and the grating reading head assembly are respectively disposed on a corresponding individual motion system mover.

[0012] The following motion system includes two linear modules mounted on the frame that follow the movement of the two motion system movers, and each linear module is equipped with a corresponding vacuum bellows.

[0013] The vacuum bellows is used in conjunction with the laser interferometer, and its movable end moves back and forth with the motion system, so that most of the optical path of the laser interferometer is located in a vacuum environment.

[0014] In one embodiment, the two motion system movers are a motion system X-axis mover and a motion system Y-axis mover, the motion system X-axis mover is located above the motion system Y-axis mover, and the planar grating assembly is disposed on the motion system Y-axis mover;

[0015] The X-axis mover of the motion system performs stepping motion, and the Y-axis mover of the motion system performs scanning motion. The grating reading head assembly is mounted on the X-axis mover of the motion system and is used to provide relative displacement changes for the measuring instrument (laser interferometer assembly and grating reading head assembly) and the measured object (mirror assembly and calibrated plane grating assembly).

[0016] In one embodiment, the frame includes a first frame, a second frame, and a vibration isolation mechanism disposed between the first frame and the second frame, wherein the first frame is in direct contact with the ground;

[0017] The first frame is a metal frame, the second frame is a granite frame, and the vibration isolation mechanism consists of multiple vibration isolators. The metal frame is in direct contact with the ground, and the granite frame is connected to the metal frame through the vibration isolators. The vibration isolators are evenly distributed on the metal frame. The metal frame is used to support vibration sources such as the following motion system and the vacuum bellows assembly. To achieve a good vibration isolation effect, the granite frame is separated from the metal frame by the vibration isolators and is used to support the motion system, the planar grating assembly, the grating reading head assembly, the laser interferometer assembly, and the reflector assembly, etc.

[0018] In one embodiment, the first frame includes a base plate and a first portal frame horizontally disposed on the base plate. The two linear modules are an X-axis linear module and a Y-axis linear module. The base plate is provided with a raised support frame for mounting the Y-axis linear module. The X-axis linear module is mounted on the top of the first portal frame. The two vacuum bellows are an X-axis vacuum bellows and a Y-axis vacuum bellows. The X-axis vacuum bellows is fixed on the X-axis linear module, and the Y-axis vacuum bellows is fixed on the Y-axis linear module.

[0019] In one embodiment, both the X-axis linear module and the Y-axis linear module are composed of servo motors and linear guides, ensuring that the X-axis vacuum bellows and the Y-axis vacuum bellows move synchronously with the X-axis mover and the Y-axis mover of the motion system, respectively.

[0020] In one embodiment, the second frame includes a base plate and a second portal frame horizontally arranged on the base plate. Both the base plate and the second portal frame are located on a base plate below the first portal frame. A longitudinal guide rail for supporting the Y-axis mover of the motion system is provided on the base plate opposite to the second portal frame. The X-axis mover of the motion system is located on the top crossbeam of the second portal frame and can reciprocate along the top crossbeam of the second portal frame. The base plate has an opening for the protruding support frame to pass through.

[0021] In one embodiment, the two reflectors are an X-axis reflector and a Y-axis reflector, with the X-axis reflector located on the X-axis mover of the motion system and the Y-axis reflector located on the Y-axis mover of the motion system.

[0022] The two laser interferometers are an X-axis laser interferometer and a Y-axis laser interferometer. The X-axis laser interferometer is located at one end of the second portal frame crossbeam and cooperates with the X-axis reflector. The Y-axis laser interferometer is located at one edge of the base plate and cooperates with the Y-axis reflector.

[0023] The X-direction vacuum bellows is located between the X-direction reflector and the laser interferometer (X), and the Y-direction vacuum bellows is located between the Y-direction reflector and the laser interferometer (Y).

[0024] In one embodiment, both the X-axis laser interferometer and the Y-axis laser interferometer are triaxial interferometers. Each interferometer has three measurement axes and can measure the linear displacement in the same direction at three different points. The triaxial interferometer includes an interferometer group and an incident / return signal receiver. The interferometer group is used to generate laser interference signals, and the incident / return signal receiver is used to provide input signals and receive output interference signals.

[0025] In one embodiment, the grating reading head assembly includes multiple grating reading heads, which are grating encoders or grating interferometers, and each grating reading head can measure linear displacement in two directions;

[0026] Each grating reading head includes an interferometer group and an input / return signal receiver. The interferometer group is used to generate laser interference signals, and the input / return signal receiver is used to provide input signals and receive output interference signals.

[0027] In one embodiment, the planar grating assembly includes a grating chuck and a calibrated planar grating disposed on the grating chuck.

[0028] The above-mentioned technical features can be combined in various suitable ways or replaced by equivalent technical features, as long as the purpose of the present invention can be achieved.

[0029] The grating measurement and calibration system for a lithography machine provided by this invention has at least the following advantages compared with the prior art:

[0030] 1. The technical solution proposed in this invention utilizes a following motion system and a vacuum bellows to place the necessary laser optical path in a vacuum environment, which ensures accuracy and reduces the difficulty of operation.

[0031] 2. The technical solution proposed in this invention adopts a motion system with independent motion directions (two independent motion axes). This motion structure is more stable and has higher motion accuracy than the existing technology. The reflector has no motion relative to the laser interferometer along the direction perpendicular to the laser light path. The laser interferometer measures the displacement of its own motion axis without being affected by the other motion axis, resulting in high measurement accuracy. Attached Figure Description

[0032] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0033] Figure 1 This is a schematic diagram of the rack.

[0034] Figure 2 This is a schematic diagram of the measurement direction of the laser interferometer;

[0035] Figure 3 A schematic diagram of the laser interferometer layout;

[0036] Figure 4 This is a schematic diagram of a motion-following system;

[0037] Figure 5 This is a schematic diagram showing the measurement direction of the grating reading head;

[0038] Figure 6 This is a schematic diagram of the layout of the grating reading head;

[0039] Figure 7 This is a schematic diagram of the planar grating layout of the calibrated component;

[0040] Figure 8 This is a schematic diagram showing the measurement direction of the calibration module;

[0041] Figure 9 This is a schematic diagram of the trajectory of the motion system;

[0042] Figure 10 This is a schematic diagram of the assembly of a lithography machine grating measurement and calibration system according to the present invention.

[0043] Figure label:

[0044] 10. Motion system; 11. X-axis mover of the motion system; 12. Y-axis mover of the motion system; 20. Planar grating assembly; 21. Planar grating to be calibrated; 22. Grating chuck; 30. Grating reading head assembly; 31. Grating reading head one; 32. Grating reading head two; 33. Grating reading head three; 34. Grating reading head four; 40. Laser interferometer assembly; 41. X-axis laser interferometer; 42. Y-axis laser interferometer; 50. Follower motion system; 51. X-axis linear module; 52. Y-axis linear module; 60. Vacuum bellows assembly; 61. X-axis vacuum bellows; 62. Y-axis vacuum bellows; 70. Mirror assembly; 71. X-axis mirror; 72. Y-axis mirror; 80. Frame; 81. First frame; 82. Second frame; 83. Vibration isolation mechanism. Detailed Implementation

[0045] The invention will now be further described with reference to the accompanying drawings.

[0046] like Figure 1-10 As shown, an embodiment of the present invention provides a grating measurement and calibration system for a lithography machine, including a frame 80, and further including a motion system 10 with mutually independent motion directions, a planar grating assembly 20, a grating reading head assembly 30, a laser interferometer assembly 40, a following motion system 50, a vacuum bellows assembly 60, and a reflector assembly 70;

[0047] The motion system 10 is mounted on the frame 80 and includes two motion system movers with opposite and perpendicular motion directions. The planar grating assembly 20 and the grating reading head assembly 30 are respectively mounted on a single motion system mover.

[0048] The mirror assembly 70 includes two mirrors fixed on the two moving parts of the two motion systems, and the mirror surface of each mirror is perpendicular to the motion direction of its corresponding moving part; the laser interferometer assembly 40 includes two laser interferometers fixed on the frame 80, and each laser interferometer is matched with the corresponding mirror as a measurement reference.

[0049] The following motion system 50 includes two linear modules mounted on the frame 80 that follow the motion of the two motion system movers respectively. The vacuum bellows assembly 60 includes two vacuum bellows mounted on the two linear modules respectively, with each vacuum bellows located between the corresponding laser interferometer and the reflector.

[0050] The vacuum bellows works in conjunction with the laser interferometer, and its movable end reciprocates with the motion system 10, the purpose of which is to ensure that most of the optical path of the laser interferometer is located in a vacuum environment.

[0051] In one embodiment, the two motion system movers are motion system X-direction mover 11 and motion system Y-direction mover 12, the motion system X-direction mover 11 is located above the motion system Y-direction mover 12, and the planar grating assembly 20 is disposed on the motion system Y-direction mover 12;

[0052] The X-axis mover 11 of the motion system realizes stepping motion, and the Y-axis mover 12 of the motion system realizes scanning motion. The grating reading head assembly 30 is disposed on the X-axis mover 11 of the motion system and is used to provide relative displacement changes for the measuring instrument (laser interferometer assembly 40 and grating reading head assembly 30) and the measured object (reflector assembly 70 and calibrated plane grating assembly 20).

[0053] In one embodiment, such as Figure 1 As shown, the frame 80 includes a first frame 81, a second frame 82, and a vibration isolation mechanism 83 disposed between the first frame 81 and the second frame 82. The first frame 81 is in direct contact with the ground.

[0054] The first frame 81 is a metal frame, the second frame 82 is a granite frame, and the vibration isolation mechanism 83 consists of multiple vibration isolators. The metal frame is in direct contact with the ground, and the granite frame is connected to the metal frame through the vibration isolators. The vibration isolators are evenly distributed on the metal frame. The metal frame is used to support vibration sources such as the following motion system 50 and the vacuum bellows assembly 60. To achieve a good vibration isolation effect, the granite frame is separated from the metal frame by vibration isolators and is used to support the motion system 10, the planar grating assembly 20, the grating reading head assembly 30, the laser interferometer assembly 40, and the reflector assembly 70.

[0055] In one embodiment, the first frame 81 includes a base plate and a first portal frame horizontally arranged on the base plate. The two linear modules are an X-axis linear module 51 and a Y-axis linear module 52. The base plate is provided with a raised support frame for mounting the Y-axis linear module 52. The X-axis linear module 51 is mounted on the top of the first portal frame. The two vacuum bellows are an X-axis vacuum bellows 61 and a Y-axis vacuum bellows 62. The X-axis vacuum bellows 61 is fixed on the X-axis linear module 51, and the Y-axis vacuum bellows 62 is fixed on the Y-axis linear module 52.

[0056] In one embodiment, both the X-axis linear module 51 and the Y-axis linear module 52 are composed of servo motors and linear guides, ensuring that the X-axis vacuum bellows 61 and the Y-axis vacuum bellows 62 move synchronously with the X-axis mover 11 and the Y-axis mover 12 of the motion system, respectively. Figure 4 As shown, when the laser interferometer and the reflector are relatively displaced, the linear module drives the vacuum bellows to adjust its position, thereby ensuring that the laser optical path is always in a vacuum environment, thus ensuring the measurement accuracy of the measurement system.

[0057] In one embodiment, the second frame 82 includes a base plate and a second portal frame arranged laterally on the base plate. Both the base plate and the second portal frame are located on a base plate below the first portal frame. The base plate opposite the second portal frame is provided with a longitudinal guide rail for supporting the Y-axis mover 12 of the motion system. The X-axis mover 11 of the motion system is located on the top crossbeam of the second portal frame and can reciprocate along the top crossbeam of the second portal frame. The base plate has an opening for the protruding support frame to pass through.

[0058] In one embodiment, the two reflectors are an X-axis reflector 71 and a Y-axis reflector 72, with the X-axis reflector 71 located on the X-axis mover 11 of the motion system and the Y-axis reflector 72 located on the Y-axis mover 12 of the motion system.

[0059] The two laser interferometers are an X-axis laser interferometer 41 and a Y-axis laser interferometer 42. The X-axis laser interferometer 41 is located at one end of the second portal frame crossbeam and cooperates with the X-axis reflector 71. The Y-axis laser interferometer 42 is located at one edge of the base plate and cooperates with the Y-axis reflector 72.

[0060] The X-direction vacuum bellows 61 is located between the X-direction reflector 71 and the laser interferometer (X direction), and the Y-direction vacuum bellows 62 is located between the Y-direction reflector 72 and the laser interferometer (Y direction).

[0061] In one embodiment, the X-axis laser interferometer 41 and the Y-axis laser interferometer 42 are both triaxial interferometers. Each interferometer has three measurement axes and can measure the linear displacement in the same direction at three different points. The triaxial interferometer includes an interferometer group and an incident / return signal receiver. The interferometer group is used to generate laser interference signals, and the incident / return signal receiver is used to provide input signals and receive output interference signals.

[0062] Specifically, such as Figure 2 As shown, this is a schematic diagram of the measurement direction of the X-axis laser interferometer 41. Taking the X-axis measurement as an example, each laser interferometer has three measurement axes X1, X2, and X3. The average value of the three axes is the X-axis linear position measurement value. The combination of X1 and X2 can measure the Z-axis rotation angle RZ. Similarly, the combination of X1 and X3 or X2 and X3 can measure the Y-axis rotation angle RY. Therefore, the three-axis laser interferometer can measure the linear position in one direction and the rotation angles in the other two directions.

[0063] like Figure 3 The diagram shows the layout of the X-axis laser interferometer 41 and the Y-axis laser interferometer 42. The X-axis laser interferometer 41 and the Y-axis laser interferometer 42 can measure the linear displacement of the motion system in the X and Y directions, as well as the rotation angles around the X, Y, and Z directions.

[0064] In one embodiment, the grating reading head assembly 30 includes four grating reading heads, which are grating encoders or grating interferometers, and each grating reading head can measure linear displacement in two directions;

[0065] Each grating reading head includes an interferometer group and an input / return signal receiver. The interferometer group is used to generate laser interference signals, and the input / return signal receiver is used to provide input signals and receive output interference signals.

[0066] Specifically Figure 5 This is a schematic diagram of the measurement direction of the grating reading head. Each grating reading head can measure linear displacement in two directions. When the grating reading head has relative displacement with the plane grating 21 of the calibrated part along the X direction, the grating reading head can measure the linear displacement parallel to the X direction; when the grating reading head has relative displacement with the plane grating 21 of the calibrated part in the Z direction, the grating reading head can measure the linear displacement in the Z direction.

[0067] like Figure 6 and Figure 7The diagram shows the layout of the grating reading heads and the planar grating of the calibrated component. The four grating reading heads are designated as Grating Reading Head 1 (31), Grating Reading Head 2 (32), Grating Reading Head 3 (33), and Grating Reading Head 4 (34), and are fixed at the four corners below the X-axis mover of the motion system. The planar grating 21 of the calibrated component is fixed to the grating chuck 22, which is fixed to the Y-axis mover 12 of the motion system. The planar grating 21, the grating chuck 22, and the Y-axis mover 12 of the motion system are closely distributed along the Z-axis (vertical direction).

[0068] like Figure 8 The diagram shows the measurement direction of the calibration module. In this embodiment, grating reading head 1 (31) and grating reading head 33 (33) can measure the linear displacements X1 and X2 parallel to the planar grating along the X direction, and the linear displacements Z1 and Z3 along the Z direction (vertical direction); grating reading head 2 (32) and grating reading head 4 (34) can measure the linear displacements Y1 and Y2 parallel to the calibrated planar grating 21 along the X and Y directions (lateral and longitudinal directions), and the linear displacements Z2 and Z4 along the Z direction (vertical direction); therefore, the combination of the linear displacements X1, X2, Y1, Y2, Z1, Z2, Z3, and Z4 measured by the four grating reading heads can measure the pose of the planar grating in space, that is, the linear displacements of the calibrated planar grating 21 in the X, Y, and Z directions, as well as the rotation angles around the X, Y, and Z directions. In this implementation case, the layout scheme of the grating reading head is not unique, the number of grating reading heads is not unique, and the installation direction of the grating reading head is not unique. As long as all grating reading heads can simultaneously measure the linear displacement of the X and Y directions, and three or more Z-direction positions, the pose of the calibrated planar grating 21 in space can be solved.

[0069] In one embodiment, the planar grating assembly 20 includes a grating chuck 22 and a calibrated planar grating 21 disposed on the grating chuck 22.

[0070] Working principle: The motion system's Y-axis mover carries the planar grating assembly 20 in a scanning motion along the Y-axis. After completing the scanning stroke, the motion system's X-axis mover carries the grating reading head assembly 30 in a stepping motion along the X-axis. This scanning and stepping motion is repeated until the motion trajectory completely covers the surface of the calibrated part. Figure 9 As shown. During the calibration process, the data measured by the four grating reading heads are processed to obtain the linear displacements in the X and Y directions, as well as the rotation angles around the X, Y, and Z axes respectively (the Z-direction linear displacement is not measured). Simultaneously, the data measured by the two laser interferometers are also processed to obtain the linear displacements in the X and Y directions, as well as the rotation angles around the X, Y, and Z axes respectively. Comparing the real-time data obtained from both methods completes the calibration. It is worth noting that the measurement of the Z-direction linear displacement is related to the laser wavelength and is independent of the grating pitch of the planar grating on the calibrated component; therefore, it is unnecessary to measure the Z-direction linear displacement.

[0071] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0072] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A grating measurement and calibration system for a lithography machine, comprising a frame, characterized in that, It also includes a motion system with at least two degrees of freedom whose motion directions are independent of each other, a planar grating assembly, a grating reading head assembly, and a follower motion system that links the motion systems; The planar grating assembly and the grating reading head assembly are respectively mounted on a separate degree-of-freedom component of the motion system. A reflector is provided on both the degree-of-freedom component on which the planar grating assembly is mounted and the degree-of-freedom component on which the grating reading head assembly is mounted. The frame is equipped with a laser interferometer that mates with each reflector; a vacuum bellows is installed between the corresponding laser interferometer and the reflector, and the vacuum bellows is installed on the following motion system and moves synchronously with the motion system; The motion system is a two-degree-of-freedom motion system mounted on the frame. The two-degree-of-freedom components are two motion system movers with opposite and perpendicular motion directions. The planar grating assembly and the grating reading head assembly are respectively set on the corresponding individual motion system mover. The following motion system includes two linear modules mounted on the frame that follow the movement of the two motion systems' movers, with each linear module equipped with a corresponding vacuum bellows; The two motion system movers are the X-axis motion system mover and the Y-axis motion system mover, respectively. The X-axis motion system mover is located above the Y-axis motion system mover, and the planar grating assembly is disposed on the Y-axis motion system mover. The two vacuum bellows are an X-direction vacuum bellows and a Y-direction vacuum bellows; The two reflectors are an X-axis reflector and a Y-axis reflector. The X-axis reflector is located on the X-axis mover of the motion system, and the Y-axis reflector is located on the Y-axis mover of the motion system. The two laser interferometers are an X-axis laser interferometer and a Y-axis laser interferometer. The X-axis vacuum bellows is located between the X-axis reflector and the X-axis laser interferometer, and the Y-axis vacuum bellows is located between the Y-axis reflector and the Y-axis laser interferometer.

2. The lithography machine grating measurement and calibration system according to claim 1, characterized in that, The frame includes a first frame, a second frame, and a vibration isolation mechanism disposed between the first frame and the second frame, wherein the first frame is in direct contact with the ground. The first frame includes a base plate and a first portal frame horizontally arranged on the base plate. The two linear modules are an X-axis linear module and a Y-axis linear module. The base plate is provided with a raised support frame for mounting the Y-axis linear module. The X-axis linear module is mounted on the top of the first portal frame. The X-axis vacuum bellows is fixed on the X-axis linear module, and the Y-axis vacuum bellows is fixed on the Y-axis linear module.

3. The lithography machine grating measurement and calibration system according to claim 2, characterized in that, Both the X-axis linear module and the Y-axis linear module are composed of servo motors and linear guides, ensuring that the X-axis vacuum bellows and the Y-axis vacuum bellows move synchronously with the X-axis mover and the Y-axis mover of the motion system, respectively.

4. The lithography machine grating measurement and calibration system according to claim 2, characterized in that, The second frame includes a base plate and a second portal frame horizontally arranged on the base plate. Both the base plate and the second portal frame are located on a base plate below the first portal frame. The base plate opposite the second portal frame is provided with a longitudinal guide rail for supporting the Y-axis mover of the motion system. The X-axis mover of the motion system is located on the top crossbeam of the second portal frame and can reciprocate along the top crossbeam of the second portal frame. The base plate has an opening for the protruding support frame to pass through.

5. The lithography machine grating measurement and calibration system according to claim 4, characterized in that, The X-axis laser interferometer is located at one end of the second portal frame beam and cooperates with the X-axis reflector, while the Y-axis laser interferometer is located at one edge of the base plate and cooperates with the Y-axis reflector.

6. The lithography machine grating measurement and calibration system according to claim 5, characterized in that, Both the X-axis and Y-axis laser interferometers are triaxial interferometers. Each interferometer has three measurement axes and can measure the linear displacement in the same direction at three different points. The triaxial interferometer includes an interferometer group and an incident / return signal receiver. The interferometer group is used to generate laser interference signals, and the incident / return signal receiver is used to provide input signals and receive output interference signals.

7. The lithography machine grating measurement and calibration system according to claim 1, characterized in that, The grating reading head assembly includes multiple grating reading heads, which are grating encoders or grating interferometers. Each grating reading head can measure linear displacement in two directions. Each grating reading head includes an interferometer group and an input / return signal receiver. The interferometer group is used to generate laser interference signals, and the input / return signal receiver is used to provide input signals and receive output interference signals.

8. The lithography machine grating measurement and calibration system according to claim 1 or 7, characterized in that, The planar grating assembly includes a grating chuck and a calibrated planar grating disposed on the grating chuck.

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