Photolithography machine, motion stage positioning measurement system and working method thereof

Abstract

The present invention provides a photolithography machine, a moving stage positioning and measurement system and a working method thereof. A blowing device is arranged in the moving stage positioning and measurement system. The blowing device is installed in the reading head area of ​​the moving stage and moves with the moving stage. The blowing device is used to blow ion gas to the surface of the plane grating to remove static electricity on the grating surface, reduce particulate matter adsorbed due to static electricity, and maintain the cleanliness of the grating scale optical path. The blowing device can also clean and take away particles on the surface of the grating scale, maintain the surface cleanliness, maintain stable measurement accuracy, reduce particulate matter adsorbed on the surface of the plane grating, maintain the cleanliness of the grating scale optical path, and can provide more accurate position measurement for the full-stroke working scene of the moving stage. The moving stage positioning and measurement system does not need to drag the moving stage and the plane grating out of the photolithography machine for cleaning, thereby ensuring the full-stroke working scene of the moving stage, providing more accurate position measurement and improving work efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photolithography equipment and systems, and in particular to a photolithography machine, a motion stage positioning and measuring system and a working method thereof. Background Art

[0002] As integrated circuits develop rapidly towards large-scale and high-integration, the requirements for overlay accuracy of lithography machines are becoming increasingly higher. Correspondingly, the accuracy of obtaining the six-degree-of-freedom position information of the motion stage and mask stage is also improved.

[0003] In contrast, the optical path of the grating ruler measurement system can be very small (usually a few millimeters), and its optical path is independent of the measurement range. It has the characteristics of high measurement stability, simple structure, and easy miniaturization, which makes it occupy an important position in the field of nano-measurement. In the new generation of lithography systems, the grating ruler measurement system has begun to gradually replace the interferometer and undertake high-precision, high-stability, and picometer-precision measurement tasks.

[0004] At present, the cleaning of the grating ruler on the moving stage of the lithography machine is mainly done by blowing clean gas to the surface of the grating ruler on the moving stage through a cleaning device installed above the moving stage, so as to blow away the contaminated particles on the grating ruler and reduce the influence of the particles on the grating measurement accuracy. However, the above method is only applicable to dry lithography devices with the grating plane located on the moving stage, but the static electricity on the surface of the plane grating cannot be eliminated or reduced. In addition, the immersion lithography machine with the plane grating located above the moving stage cannot use the above method to clean the static electricity and contaminated particles on the surface of the plane grating. Summary of the invention

[0005] The object of the present invention is to provide a photolithography machine, a motion stage positioning measurement system and a working method thereof, so as to solve the problems of static electricity and contamination particles on the surface of the planar grating of an immersion photolithography machine.

[0006] In order to solve the above technical problems, the present invention provides a moving table positioning and measurement system, which includes a reference frame, a read head, a plane grating, a moving table and a blowing device, wherein the read head is mounted on the moving table, the plane grating is mounted on the reference frame, the blowing device is used to clean the plane grating, and the blowing device is mounted on the moving table and can move with the moving table.

[0007] Optionally, the system further comprises a grating mounting plate, and the plane grating is mounted on the reference frame via the grating mounting plate.

[0008] Optionally, the moving platform has a reading head area, the reading head is installed on the reading head area and the reading head can move following the moving platform, and the blowing device is installed on the reading head area.

[0009] Optionally, the blowing and exhausting device includes a gas ion generating unit, a blowing and exhausting diverter block and an exhaust device, wherein the gas ion generating unit is used to ionize clean air, the blowing and exhausting diverter block uses the ionized clean air to purge the plane grating, and the exhaust device is used to extract contaminated particles on the plane grating.

[0010] Optionally, the gas ion generating unit includes a point ionization device and a gas flow channel, the point ionization device is used to ionize clean air into an ion flow that neutralizes static electricity on the surface of the planar grating, and the gas flow channel is used to transport the ionized clean air to the exhaust diversion block.

[0011] Optionally, the blowing and exhaust diverter block comprises a cavity, an upper cavity cover and a lower cavity cover, and the upper cavity cover and the lower cavity cover are closed to form the cavity.

[0012] Optionally, the lower cavity cover is provided with an air inlet and an exhaust recovery port, and the upper cavity cover is provided with an annular air blowing port.

[0013] Optionally, the reader head is located in the middle of the annular air blowing port, and the annular air blowing port can form an air curtain surrounding the reader head area, so that the pollutant particles blown off the surface of the planar grating can be extracted through the exhaust recovery port.

[0014] Optionally, the width of the annular air blowing port is 0.5mm-1.5mm.

[0015] Optionally, the annular air outlet includes a plurality of discontinuous air outlet units.

[0016] Optionally, the extraction and recovery port is arranged around the reading head area.

[0017] Based on the same inventive concept, the present invention also provides a photolithography machine, which adopts any of the above-mentioned motion stage positioning and measurement systems.

[0018] Based on the same inventive concept, the present invention provides a working method of a motion platform positioning and measuring system, comprising:

[0019] Step 1: The light source of the motion stage positioning measurement system emits light;

[0020] Step 2, the blowing device blows out the ionized clean air toward the plane grating;

[0021] Step 3: whether the plane grating measurement error meets the error threshold requirement; when the measurement error meets the error threshold requirement, step 4 is executed; when the grating measurement error does not meet the error threshold requirement, the blowing device extracts the polluted particles, and then step 2 is continued;

[0022] Step 4: The motion stage positioning and measurement system continues to work.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a photolithography machine, a moving stage positioning and measurement system and a working method thereof. A blowing device is arranged in the moving stage positioning and measurement system. The blowing device is installed on the moving stage and moves with the moving stage. The blowing device is used to blow ion gas onto the surface of the plane grating to remove static electricity on the grating surface, reduce particulate matter adsorbed due to static electricity, maintain the cleanliness of the grating scale optical path, and provide more accurate position measurement for the full-stroke working scene of the moving stage. The blowing device can also clean and take away particles on the surface of the grating scale, maintain the surface cleanliness, maintain stable measurement accuracy, reduce particulate matter adsorbed on the surface of the plane grating, maintain the cleanliness of the grating scale optical path, and provide more accurate position measurement for the full-stroke working scene of the moving stage. The moving stage positioning and measurement system does not need to drag the moving stage and the plane grating out of the photolithography machine for cleaning, thereby ensuring the full-stroke working scene of the moving stage, providing more accurate position measurement while improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic structural diagram of a motion platform positioning and measuring system according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of a blowing and exhausting device of a motion platform positioning and measuring system according to an embodiment of the present invention;

[0027] Figure 3 2 is a schematic diagram of the structure of a gas ion generating unit of a moving stage positioning and measuring system according to an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the lower chamber cover of the blow-out shunt block structure of the motion table positioning and measuring system according to an embodiment of the present invention;

[0029] Figure 5 2 is a schematic diagram of the structure of the blow-off and discharge shunt block of the motion table positioning and measurement system according to an embodiment of the present invention;

[0030] Figure 6 Schematic diagram of the working process of the blow-out shunt block of the motion table positioning and measuring system according to an embodiment of the present invention;

[0031] Figure 7 Schematic diagram of the structure of the upper cavity cover of the discontinuous annular tuyere of the positioning and measuring system of the motion platform according to the embodiment of the present invention;

[0032] Figure 8 is a flow chart of the working method of the motion platform positioning and measuring system according to an embodiment of the present invention;

[0033] In the figure,

[0034] 100-reference frame; 200-grating mounting plate; 300-plane grating 400-moving table; 500-reading head; 600-grating scale optical path; 700-blowing device; 701-gas ion generating unit; 702-blowing diverter block; 703-exhaust device; 7011-point ionization device; 7012-gas flow channel; 7021-lower cavity cover; 7022-air inlet; 7023-exhaust recovery port; 7024-cavity; 7025-upper cavity cover; 7026-annular air outlet. DETAILED DESCRIPTION

[0035] The inventors have found through research that, according to the principle of grating diffraction, by moving in a direction perpendicular to the grating lines, the displacement in the direction of movement can be obtained. In order to obtain horizontal X and Y displacements, a two-dimensional plane grating with lines in two directions is required. The plane grating and the detection device are arranged relative to each other. The detection device can detect the interference of the +1 and -1 order diffraction light in the X direction and produce a phase difference, and the interference of the +1 and -1 order diffraction light in the Y direction and produce a phase difference, so that the X and Y displacements can be calculated. When the grating moves in the Z direction or the detection device moves in the Z direction, the detection device can detect the phase change, so that the Z displacement can be calculated. Based on a plane grating, three degrees of freedom, X, Y, and Z, can be obtained. In order to obtain multi-degree-of-freedom position information, multiple plane gratings and multiple detection devices need to be combined together to achieve it.

[0036] The motion stage positioning measurement system is mainly used to measure the position information of the six degrees of freedom of the motion stage: X, Y, Z, Rx, Ry and Rz. In order to achieve this function, two grating mounting plates are usually installed on the reference frame of the motion stage positioning measurement system, and four plane gratings are installed on the two grating mounting plates; each motion stage has four readers, which are installed on the motion stage and move with the motion stage. The direction of the plane grating of the motion stage is consistent with the measurement direction of the reader on the motion stage. The combined switching strategy of multiple gratings and multiple readers is adopted to achieve high-precision control within the full range of the motion stage of the lithography machine.

[0037] When the plane grating moves at high speed relative to the motion stage, due to the small distance between the two (about 10mm), the plane grating is made of microcrystalline glass, so the grating will generate static electricity, causing particle adsorption. The accumulated adsorbed particles will be distributed between the grids on the grating surface, which can easily cause technical errors in the reader and affect the measurement and positioning accuracy of the motion stage.

[0038] Based on the demand for measurement accuracy control of a moving stage positioning and measurement system in a lithography machine, the present invention proposes a lithography machine, a moving stage positioning and measurement system and a working method thereof, which can realize electrostatic control and operation of a plane grating surface under the requirements of a large grating area, a large number of gratings, and high requirements for grating surface cleanliness and cleaning operation, thereby ensuring the measurement accuracy of the moving stage positioning and measurement system.

[0039] The following is a further detailed description of the lithography machine, the motion stage positioning measurement system and the working method thereof proposed in the present invention in combination with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0040] Figure 1 FIG. 1 is a schematic diagram of the structure of the motion platform positioning and measuring system according to an embodiment of the present invention. Figure 1 As shown, this embodiment provides a moving stage positioning measurement system, the system comprising a reference frame 100, a grating mounting plate 200, a plane grating 300, a moving stage 400, a reader 500 and a blow-off device 700. The plane grating 300 is mounted on the grating mounting plate 200. The grating mounting plate 200 is mounted on the reference frame 100. The reader 500 is mounted on the moving stage 400 and can move with the moving stage 400. The blow-off device 700 is mounted on the moving stage 400 in the reader 500 area and can move with the moving stage 400. The light source emitted by the reader 500 reaches the reader 500 area through the plane grating 300, forming a grating scale optical path 600.

[0041] In this embodiment, the motion stage positioning measurement system is provided with at least two grating mounting plates 200 and two workbenches 400. The grating mounting plates 200 are evenly mounted below the reference frame 100. The two workbenches 400 are located below the two grating mounting plates 200. Four reading heads 500 are provided on each motion stage 400, and the four reading heads 500 are respectively arranged at the four corners of the motion stage 400, and the four reading heads 500 can move with the motion stage 400.

[0042] When it is necessary to remove static electricity and particle contamination in a certain area on the plane grating 300, the blowing device 700 blows clean ion gas at a certain wind speed toward the plane grating 300, and recovers power through the exhaust of the blowing device 700 to eliminate static electricity on the grating surface and take away the contaminated particles, thereby eliminating static electricity on the grating surface and exhausting the contaminated particles.

[0043] Figure 2 FIG. 1 is a schematic diagram of the blowing and exhausting device of the motion platform positioning and measuring system according to an embodiment of the present invention. Figure 2 As shown, the blowing device 700 is installed on the moving table 400, and blows clean ion gas at a certain angle and wind speed toward the plane grating 300 through the gap between the plane grating 300 and the moving table 400, and recovers power through the exhaust of the blowing device 700, thereby eliminating static electricity on the grating surface and taking away polluted particles, thereby ensuring the measurement accuracy of the grating measurement system and the position control accuracy of the moving table.

[0044] In this embodiment, the blowing device 700 includes a gas ion generating unit 701, a blowing and exhausting flow block 702, and an exhaust device 703. Clean air is ionized by the gas ion generating unit 701 after passing through the gas ion generating unit 701, and ionized clean air enters the blowing and exhausting flow block 702, and the plane grating 300 area is purged through the air outlet of the blowing and exhausting flow block 702. The ions in the clean air eliminate the static electricity of the plane grating 300, and the purging force of the clean air can blow the polluted particles on the plane grating 300 away from the surface of the plane grating 300. The blowing and exhausting flow block 702 is provided with an exhaust port connected to the exhaust device 703, and the exhaust device 703 recovers power to eliminate the static electricity on the surface of the plane grating 300 and take away the polluted particles.

[0045] In the preferred solution, the wind speed that removes static electricity from the surface of the plane grating 300 and carries away the polluted particles is calculated as follows:

[0046] First, according to the van der Waals mechanics model between the pollution particles on the smooth plane and the non-smooth surface, the van der Waals force between the surface of the plane grating 300 and the pollution particles is approximately:

[0047]

[0048] In formula (1), A is the normal force coefficient; r is the approximate radius of the protrusion on the surface of the pollution particle; R is the equivalent radius of the pollution particle; z is the distance between the geometric center of the pollution particle and the plane, F f is the van der Waals force between the plane grating surface and the contamination particles.

[0049] Second, the mechanical model of the electrostatic equilibrium adsorption force between the surface of the plane grating 300 and the contaminant particles is approximately:

[0050]

[0051] In formula (2), ε is the free space dielectric constant; U is the micro voltage; R is the equivalent radius of the pollution particle; Z is the distance between the geometric center of the pollution particle and the plane, and F e It is the electrostatic equilibrium adsorption force between the surface of the plane grating 300 and the contamination particles.

[0052] Third, according to the Bernoulli equation, the equivalent sweeping force on the particles is:

[0053] F=0.25ρπr 2 v 2 (3)

[0054] In formula (3), ρ is the air density in the area where the particle is located; r is the approximate radius of the protrusion on the surface of the polluted particle; v is the effective wind speed of the airflow of the blowing device reaching the plane grating surface, and F is the equivalent sweeping force on the particle.

[0055] Therefore, if the particles are blown away from the plane grating surface, the wind force on the polluted particles needs to be greater than the adhesion force (van der Waals force and electrostatic force) between the particles and the grating plane. Therefore, the relationship between wind speed and polluted particles and electrostatic related parameters can be obtained as follows:

[0056]

[0057] Where: A is the normal force coefficient; r is the approximate radius of the protrusion on the surface of the polluted particle; R is the radius of the polluted particle; Z is the distance between the geometric center of the polluted particle and the plane; ε is the dielectric constant of free space; U is the micro voltage; ρ is the air density in the area where the particle is located; v is the effective wind speed of the airflow of the blowing device reaching the plane grating surface.

[0058] Figure 3 FIG. 1 is a schematic diagram of the structure of a gas ion generating unit of a moving platform positioning and measuring system according to an embodiment of the present invention. Figure 3 As shown, the gas ion generating unit 701 includes a point ionizing device 7011 and a gas flow channel 7012. The gas ion generating unit 701 serves as the air inlet unit of the blowing and exhausting device 700. The gas flow channel 7012 connects a certain flow of clean air to the blowing and exhausting device 700. The clean air passes through the point ionizing device 7011 to form an ion airflow that can neutralize the static electricity on the surface of the plane grating 300, and is blown toward the surface of the plane grating 300 from the air outlet of the blowing and exhausting device 700. Specifically, one end of the gas flow channel 7012 is connected to an air pump, and the other end is connected to the air inlet of the point ionizing device 7011. The air outlet of the point ionizing device 7011 is connected to the blowing and exhausting diverter block 702.

[0059] Figure 4 1 is a schematic diagram of the lower chamber cover of the blow-out shunt block structure of the motion platform positioning and measuring system according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of the blow-out shunt block of the motion platform positioning and measurement system according to an embodiment of the present invention; please refer to Figure 4 and Figure 5The blow-out flow diverter block 702 includes an upper cavity cover 7025 and a lower cavity cover 7021. The upper cavity cover 7025 and the lower cavity cover 7021 are closed to form a cavity 7024 in the middle. The lower cavity cover 7021 is provided with an air inlet 7022, and the air inlet 7022 is connected to one end of the gas flow channel 7012. The upper cavity cover 7025 is provided with an annular air outlet 7026. The reader 500 is located in the middle of the blow-out flow diverter block 702, and a suction and recovery port 7023 is formed in the gap with the blow-out flow diverter block 702. The suction and recovery port 7023 is arranged around the reader 500 area. The blow-out flow diverter block 702 is installed in the reader 500 area to protect the surface of the plane grating 300 in the measurement area and measure the cleanliness of the grating ruler optical path 600. The upper cavity cover 7025 and the lower cavity cover 7021 are pentagonal structures. By adopting the upper cavity cover 7025 and the lower cavity cover 7021, different outlet wind speeds can be obtained by designing the air outlet sizes of different cavity covers, wherein the width of the annular air outlet 7026 is, for example, 0.5mm-1.5mm, and the angle of the annular air outlet 7026 is the inclination angle of the edge of the gap, the maximum angle of the angle is not greater than 90 degrees, and the minimum angle is determined by the distance between the moving table 400 and the plane grating 300 when working online.

[0060] Figure 6 This is a schematic diagram of the working process of the blow-out shunt block of the motion platform positioning and measurement system according to an embodiment of the present invention. Figures 4 to 6 , the ionized clean air reaches the cavity 7024 of the blow and exhaust diverter block 702 through the air inlet 7022, and sweeps the surface of the plane grating 300 through the annular blowing port 7026. By controlling the gap size and angle of the annular blowing port 7026, the flow rate and direction of the purge airflow can be controlled to optimize the blowing effect. In order to achieve uniform air volume, multiple air inlets can also be set. At the same time, the annular blowing port 7026 can form an air curtain surrounding the area of ​​the reader 500, so that the pollutant particles blown off the surface of the plane grating 300 are extracted through the exhaust recovery port 7023, so as not to spread to other locations to cause secondary pollution.

[0061] Figure 7 This is a schematic diagram of the upper cavity cover structure of the discontinuous annular tuyere of the motion platform positioning and measurement system according to an embodiment of the present invention. Figure 7, the annular air outlet 7026 on the upper cavity cover 7025 can also be composed of discontinuous air outlet units; the spacing range of the discontinuous air outlet units is 1-5 times the width of the air outlet units, and the shape of the air outlet units is, for example, a spaced circular or slender slit shape, so as to increase the outlet wind speed. Specifically, the upper cavity cover 7025 is used to guide the airflow, so that the airflow in the cavity 7024 blows toward the surface of the plane grating at a certain speed and angle. This airflow is used to overcome the adhesion force (mainly van der Waals force) between the polluted particles and the plane grating 300, and blow the particles away from the surface of the plane grating 300. At the same time, the slender annular air outlet of the upper cavity cover 7025 structure can form an air curtain surrounding the area of ​​the reader 500, reducing the diffusion of polluted particles. The polluted particles blown away from the surface of the plane grating 300 are extracted through the exhaust recovery port 7023 of the exhaust diversion block 702, so as not to spread to other locations and cause secondary pollution. Through simulation analysis, the optimized structure of the discontinuous annular air outlet is found, which increases the airflow outlet velocity while reducing the interference of the airflow on the grating plane.

[0062] Based on the same inventive concept, this embodiment further provides a lithography machine, which adopts the above-mentioned motion stage positioning and measurement system, and the lithography machine is, for example, an immersion lithography machine.

[0063] Please refer to Figure 8 , Figure 8 : is a flow chart of a working method of a moving platform positioning and measuring system according to an embodiment of the present invention; based on the same inventive concept, the present invention also provides a working method of a moving platform positioning and measuring system, comprising:

[0064] Step 1: The light source of the motion stage positioning measurement system emits light;

[0065] Step 2: The blowing device blows out ionized clean air to the plane grating to reduce the accumulation of static electricity and pollutant particles on the surface of the plane grating 300;

[0066] Step three, whether the grating measurement error meets the error threshold. When the grating measurement error meets the error threshold, execute step four. When the grating measurement error does not meet the error threshold, enter the measurement system maintenance state. The measurement system maintenance state includes starting the blowing function of the exhaust device to blow away and extract the contaminated particles, and continue to execute step two; the blowing can be repeated multiple times until the grating measurement error meets the error threshold.

[0067] Step 4: The motion stage positioning and measurement system continues to work.

[0068] In summary, it can be seen that the photolithography machine, the motion stage positioning measurement system and the working method thereof in this embodiment can include a blow-off device for cleaning the plane grating, and can provide an ion gas flow for the plane grating to eliminate static electricity on the plane grating, reduce the adsorption of static electricity on particulate matter, and ensure the measurement accuracy of the system; on the other hand, the blow-off device can provide the plane grating with clean gas with a certain pressure and flow rate to remove the contaminated particles on the plane grating, reduce the influence of particulate matter on grating measurement, and ensure the accuracy of the motion stage position measurement.

[0069] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A motion stage positioning measurement system, characterized in that: The system comprises a reference frame, a reading head, a plane grating, a moving stage and a blowing device, wherein the reading head is mounted on the moving stage, the plane grating is mounted on the reference frame, the blowing device is used to clean the plane grating, and the blowing device is mounted on the moving stage and can move with the moving stage; Wherein, the blowing device includes a blowing diverter block, in which an annular blowing port is provided, and the reader is located in the middle of the annular blowing port. The annular blowing port can form an air curtain surrounding the reader to remove the pollutant particles blown away from the surface of the planar grating.

2. The motion stage positioning measurement system according to claim 1, characterized in that: The system further comprises a grating mounting plate, and the plane grating is mounted on the reference frame via the grating mounting plate.

3. The motion stage positioning measurement system according to claim 1, characterized in that: The moving platform has a reading head area, the reading head is installed on the reading head area and the reading head can move following the moving platform, and the blowing device is installed on the reading head area.

4. The motion stage positioning measurement system according to claim 1, characterized in that: The blowing and exhausting device also includes a gas ion generating unit and an exhaust device, wherein the gas ion generating unit is used to ionize clean air, the blowing and exhausting diverter block uses the ionized clean air to blow the plane grating, and the exhaust device is used to extract the polluted particles on the plane grating.

5. The motion stage positioning measurement system according to claim 4, characterized in that: The gas ion generating unit comprises a point ionizing device and a gas flow channel, wherein the point ionizing device is used to ionize clean air into an ion flow with static electricity neutralizing the surface of the plane grating, and the gas flow channel is used to transport the ionized clean air to the blowing and exhausting diverter block.

6. The motion stage positioning measurement system according to claim 4, characterized in that: The blow-off and exhaust diverter block comprises a cavity, an upper cavity cover and a lower cavity cover, and the upper cavity cover and the lower cavity cover are closed to form the cavity.

7. The motion stage positioning measurement system according to claim 6, characterized in that: The lower cavity cover is provided with an air inlet and an exhaust recovery port, and the upper cavity cover is provided with an annular air blowing port.

8. The motion stage positioning measurement system according to claim 7, characterized in that: The width of the annular air blowing port is 0.5mm-1.5mm.

9. The motion stage positioning measurement system according to claim 7, characterized in that: The annular air outlet includes a plurality of discontinuous air outlet units.

10. The motion stage positioning measurement system according to claim 7, characterized in that: The extraction and recovery port is arranged around the reading head.

11. A photolithography machine, characterized in that: A motion stage positioning and measuring system as described in any one of claims 1 to 10 is used.

12. A working method of the motion stage positioning and measuring system according to any one of claims 1 to 10, characterized in that: include: Step 1: The light source of the motion stage positioning measurement system emits light; Step 2, the blowing device blows out the ionized clean air toward the plane grating; Step 3: whether the plane grating measurement error meets the error threshold requirement; when the measurement error meets the error threshold requirement, step 4 is executed; when the grating measurement error does not meet the error threshold requirement, the blowing device extracts the polluted particles, and then step 2 is continued; Step 4: The motion stage positioning and measurement system continues to work.

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