Air floatation DD motor

Abstract

The invention discloses an air floatation DD motor which comprises a base, an air floatation stator, an air floatation rotor and a rotation driving assembly. A channel is formed in the base. The air floatation stator is fixed on the base, an air passage is arranged in the air floatation stator, and the air passage is communicated with the channel; the air floatation rotor covers the air floatation stator and is annularly arranged outside the air floatation stator, an upper axial gap, a radial gap and a lower axial gap are formed between the air floatation rotor and the air floatation stator, and the upper axial gap, the radial gap and the lower axial gap are all communicated with the air channel; the rotation driving assembly is connected to the air floatation rotor and can drive the air floatation rotor to rotate relative to the air floatation stator. The air floatation DD motor is small in axial runout and radial runout, the runout value can reach within 200 nm and even 100 nm, the precision is high, and the flatness requirement of a wafer arranged on the air floatation DD motor is met.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an air-floating DD motor. Background Art

[0002] DD (Driver) motor is a kind of rotary motor that can convert electrical energy into rotational mechanical energy. DD motor does not require an external reducer and is directly connected to the load, reducing the intermediate transmission link and having higher precision than servo motor.

[0003] However, DD motors still use mechanical ball bearings, which inevitably cause bearing clearance and mechanical friction, resulting in certain limitations in rotation accuracy. In ultra-high precision industries such as wafer inspection, the combined runout of the horizontally moving XY axis, other axes, and DD motors must be within 3μm, while the runout of general mechanical ball bearing DD motors can only reach 2-5μm, which cannot meet the accuracy requirements. This places higher demands on the accuracy of DD motors. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide an air-floating DD motor.

[0005] In order to achieve the above purpose, the technical solution provided by an embodiment of the present invention is as follows:

[0006] An air-floating DD motor, comprising:

[0007] A base, wherein a channel is provided in the base;

[0008] An air-floating stator is fixed to the base, an air passage is provided inside the air-floating stator, and the air passage is connected to the channel;

[0009] An air-floating rotor, covering the air-floating stator and being arranged in a ring outside the air-floating stator, an upper axial gap, a radial gap and a lower axial gap are formed between the air-floating rotor and the air-floating stator, and the upper axial gap, the radial gap and the lower axial gap are all connected to the air passage;

[0010] A rotation drive assembly is connected to the air-floating rotor and can drive the air-floating rotor to rotate relative to the air-floating stator.

[0011] As a further improvement of the present invention, the air-floating rotor includes a carrier and a mounting seat connected to the bottom end of the carrier, the upper axial gap is formed between the carrier and the upper surface of the air-floating stator, the radial gap is formed between the carrier and the outer peripheral surface of the air-floating stator, and the lower axial gap is formed between the mounting seat and the lower surface of the air-floating stator.

[0012] As a further improvement of the present invention, the mounting seat is connected to a circular grating, and the base is connected to a reading head, and the reading head is used to read the rotation value of the circular grating.

[0013] As a further improvement of the present invention, the upper axial gap, radial gap and lower axial gap are all 8-10 μm.

[0014] As a further improvement of the present invention, the rotary drive assembly includes a motor stator and a motor rotor coupled to the motor stator, the motor stator is fixed to the base, and the motor rotor is connected to the air-floating rotor.

[0015] As a further improvement of the present invention, it further comprises a shell, wherein the shell is arranged outside the motor stator, the motor stator and the shell are interference fit, and the shell and the base are interference fit.

[0016] As a further improvement of the present invention, it also includes a dynamic seal fixing part and a dynamic seal rotating part, wherein one end of the dynamic seal fixing part along the axial direction is connected to the base, and the other end extends into the air-floating stator, and one end of the dynamic seal rotating part along the axial direction is engaged in the dynamic seal fixing part, and the other end is located in the air-floating rotor and connected to the air-floating rotor, the top surface of the dynamic seal rotating part is lower than the bearing surface of the air-floating rotor, and the dynamic seal fixing part is respectively connected to the base and the dynamic seal rotating part.

[0017] As a further improvement of the present invention, the bearing surface of the air-floating rotor is provided with a stepped hole, and the stepped hole includes a first through hole, a second through hole and a third through hole which are sequentially connected along the axial direction and have successively decreasing hole diameters.

[0018] As a further improvement of the present invention, the matching clearance between the dynamic seal rotating component and the dynamic seal fixed component is 8-10 μm.

[0019] As a further improvement of the present invention, the height difference between the bearing surface of the air-floating rotor and the top surface of the dynamic seal rotating member is 0.5-1 mm.

[0020] As a further improvement of the present invention, a first negative pressure air circuit is arranged in the base, a second negative pressure air circuit is arranged in the dynamic seal fixing component, and a third negative pressure air circuit is arranged in the dynamic seal rotating component, and the first negative pressure air circuit, the second negative pressure air circuit and the third negative pressure air circuit are connected in sequence.

[0021] The beneficial effects of the present invention are:

[0022] The air-floating DD motor of the present invention has small axial runout and radial runout, so that the runout can reach 200nm or even 100nm, with high precision, ensuring the flatness requirement of the wafer set on the air-floating DD motor, and realizing negative pressure adsorption of the wafer by the dynamic seal fixing part and the dynamic seal rotating part compounded inside the carrier and the air-floating stator, so as to achieve the effect of directly adsorbing the wafer, greatly reducing the overall size and weight of the air-floating DD motor, and realizing lightweight wafer processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 A perspective view of a preferred embodiment of the present invention;

[0025] Figure 2 A top view of a preferred embodiment of the present invention;

[0026] Figure 3 for Figure 2 AA section view;

[0027] Figure 4 for Figure 3 A magnified schematic diagram of B;

[0028] Figure 5 This is a schematic diagram of an air floating support according to a preferred embodiment of the present invention;

[0029] Figure 6 This is a schematic structural diagram of an air-floating stator and an annular boss provided on a base in a preferred embodiment of the present invention;

[0030] Figure 7 for Figure 6 A top view of

[0031] Figure 8 for Figure 7 CC section view;

[0032] In the figure: 1, base, 11, channel, 12, reading head, 13, annular pipe, 14, annular boss, 15, first negative pressure air path, 2, air floating stator, 21, air channel, 211, first air channel, 212, second air channel, 213, third air channel, 22, throttle plug, 3, air floating rotor, 31, carrier, 311, carrier plate, 312, annular portion, 32, mounting seat, 321, circular grating, 33, bearing surface, 34, step hole, 341, first through hole, 342, second through hole, 343, third through hole, 344, step, 4, Rotary drive assembly, 41, motor stator, 42, motor rotor, 421, magnetic steel yoke plate, 422, magnetic steel, 51, upper axial gap, 52, radial gap, 53, lower axial gap, 6, outer shell, 71, dynamic seal fixing part, 710, groove, 711, second negative pressure air path, 72, dynamic seal rotating part, 721, top surface, 722, third negative pressure air path, 73, closed cavity, 74, fitting gap, 8, connector seat, 81, air inlet pipe connector, 82, air outlet pipe connector, 83, power cord connector, 84, encoder line connector. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0034] See also Figure 1-Figure 3 , Figure 5 , Figure 8 The embodiment of the present application discloses an air-floating DD motor, comprising a base 1, an air-floating stator 2, an air-floating rotor 3 and a rotary drive assembly 4. A channel 11 is provided in the base 1. The air-floating stator 2 is fixed to the base 1, and an air passage 21 is provided in the air-floating stator 2, and the air passage 21 is connected to the channel 11. The air-floating rotor 3 covers the air-floating stator 2 and is arranged around the outside of the air-floating stator 2. An upper axial gap 51, a radial gap 52 and a lower axial gap 53 are formed between the air-floating rotor 3 and the air-floating stator 2, and the upper axial gap 51, the radial gap 52 and the lower axial gap 53 are all connected to the air passage 21. The gas that enters the air passage 21 from the channel 11 and flows out from the air passage 21 is filled in the upper axial gap 51, the radial gap 52 and the lower axial gap 53, so that the air-floating rotor 3 can be suspended. The rotary drive assembly 4 is connected to the air-floating rotor 3 and can drive the air-floating rotor 3 to rotate relative to the air-floating stator 2.

[0035] In this embodiment, the air-floating rotor 3 includes a carrier 31 and a mounting seat 32 connected to the bottom end of the carrier 31. An upper axial gap 51 is formed between the carrier 31 and the upper surface of the air-floating stator 2, a radial gap 52 is formed between the carrier 31 and the outer peripheral surface of the air-floating stator 2, and a lower axial gap 53 is formed between the mounting seat 32 and the lower surface of the air-floating stator 2.

[0036] In some embodiments, the mounting seat 32 is connected to a circular grating 321, and the base 1 is connected to a reading head 12, which is used to read the rotation value of the circular grating 321. The circular grating 321 can be fixedly connected to the mounting seat 32 by screws, so as to rotate with the mounting seat 32 and the stage 31.

[0037] Specifically, the carrier 31 includes a carrier plate 311, an annular portion 312 connected to a side of the carrier plate 311 facing the base 1, the air-floating stator 2 is placed in the annular portion 312, and the mounting seat 32 is connected to a side of the annular portion 312 facing the base 1. An upper axial gap 51 is formed between the side of the carrier plate 311 facing the base 1 and the upper surface of the air-floating stator 2, and a radial gap 52 is formed between the inner side wall of the annular portion 312 and the outer peripheral surface of the air-floating stator 2.

[0038] In this embodiment, the upper axial gap 51, the radial gap 52 and the lower axial gap 53 are all 8-10 μm, so that the air bearing capacity and air bearing stiffness are relatively large.

[0039] See also Figure 4 In some embodiments, the air channel 21 at least includes a first air channel 211, a second air channel 212 and a third air channel 213, the second air channel 212 and the third air channel 213 are both connected to the first air channel 211, and the first air channel 211 is connected to the channel 11 of the base 1. The first air channel 211 penetrates the outer peripheral surface of the air-floating stator 2, the second air channel 212 penetrates the upper surface of the air-floating stator 2, and the third air channel 213 penetrates the lower surface of the air-floating stator 2. Specifically, the first air channel 211 is in an inverted L shape. An annular pipe 13 is provided on the base 1, and the annular pipe 13 is respectively connected to the channel 11 and the first air channel 211. The ends of the first air channel 211, the second air channel 212 and the third air channel 213 are all inlaid with throttle plugs 22, which can reduce the diameter of the air channel from which the gas is finally discharged, increase the pressure of the discharged gas, increase the supporting force, and improve the air-floating support stiffness. The air-floating stator 2 is evenly inlaid with a circle of throttle plugs 22 in the circumferential radial direction and the axial up-and-down direction, which are used to blow air from the side circumferential radial direction and the axial up-and-down direction to more stably support the air-floating rotor 3.

[0040] The rotary drive assembly 4 includes a motor stator 41 and a motor rotor 42 coupled to the motor stator 41. The motor stator 41 is fixed to the base 1, and the motor rotor 42 is connected to the air-floating rotor 3. After the motor stator 41 is powered on and controlled, an electromagnetic force is generated to drive the motor rotor 42 to rotate as a whole, thereby driving the air-floating rotor 3 to rotate together. Specifically, the motor rotor 42 includes a magnetic steel yoke plate 421 and a plurality of magnetic steels 422 connected to the outer peripheral surface of the magnetic steel yoke plate 421. The magnetic steel yoke plate 421 is sleeved on the air-floating rotor 3. More specifically, the magnetic steel yoke plate 421 is sleeved on the carrier 31 and bonded to the carrier 31, and the magnetic steel 422 is bonded to the magnetic steel yoke plate 421. It can be understood that the rotary drive assembly 4 is not limited to the above-mentioned motor structure, and an ultrasonic motor or the like can also be used, as long as the rotation of the air-floating rotor 3 can be achieved, which is not limited here.

[0041] See also Figure 1 , Figure 6 , Figure 7 In some embodiments, the air-floating DD motor further includes a housing 6, which is disposed outside the motor stator 41, and the motor stator 41 is interference-fitted with the housing 6, and the housing 6 is interference-fitted with the base 1. Through interference positioning, the connection strength and connection accuracy between the components are high, and the assembly accuracy is improved. Specifically, an annular boss 14 is provided on the base 1, and the housing 6 is interference-fitted on the outer side of the annular boss 14. The base 1 and the housing 6 can be connected by screws to improve stability.

[0042] In some embodiments, the air-floating DD motor further comprises a dynamic seal fixing member 71 and a dynamic seal rotating member 72. One end of the dynamic seal fixing member 71 along the axial direction is connected to the base 1, and the other end extends into the air-floating stator 2. One end of the dynamic seal rotating member 72 along the axial direction is fitted in the dynamic seal fixing member 71, and the other end is located in the air-floating rotor 3 and connected to the air-floating rotor 3. The top surface 721 of the dynamic seal rotating member 72 is lower than the bearing surface 33 of the air-floating rotor 3. The dynamic seal fixing member 71 is connected to the base 1 and the dynamic seal rotating member 72 respectively. A dynamic seal cavity is formed between the dynamic seal rotating member 72 and the seal fixing member 71, which can ensure that the dynamic seal rotating member 72 moves relative to the dynamic seal fixing member 71 without interference. At the same time, when there is negative pressure in the dynamic seal fixing member 71 and the dynamic seal rotating member 72, the negative pressure will not escape from the dynamic seal cavity between the dynamic seal fixing member 71 and the dynamic seal rotating member 72, thereby ensuring the airtightness of the negative pressure air path to a certain extent. After placing the load on the air-floating rotor 3, due to the height difference between the top surface 721 of the dynamic seal rotating part 72 and the bearing surface 33 of the air-floating rotor 3, the air-floating rotor 3, the dynamic seal rotating part 72 and the load form a closed cavity. By evacuating the closed cavity, the closed cavity forms a vacuum cavity, so that the load is adsorbed by negative pressure. It can be understood that the adsorption of the load is not limited to the negative pressure adsorption of the above structure, and static pressure adsorption can also be used.

[0043] In some embodiments, the bearing surface 33 of the air-floating rotor 3 is provided with a stepped hole 34, and the stepped hole 34 includes a first through hole 341, a second through hole 342, and a third through hole 343 which are sequentially connected in the axial direction and have decreasing apertures. The first through hole 341, the second through hole 342, and the third through hole 343 are sequentially arranged in the up-down direction, and the upper part of the dynamic seal rotating member 72 is located in the second through hole 342 and is stopped at the step 344 formed by the second through hole 342 and the third through hole 343. The upper part of the dynamic seal rotating member 72 can be connected to the air-floating rotor 3 by screws. When the load is placed on the bearing surface 33 of the air-floating rotor 3, the first through hole 341 is a closed cavity. A groove 710 is provided in the upper part of the dynamic seal fixing member 71, and the lower part of the dynamic seal rotating member 72 is placed in the groove 710. A dynamic seal cavity is formed between the inner side wall of the groove 710 and the outer peripheral surface of the lower part of the dynamic seal rotating member 72.

[0044] In this embodiment, the matching gap 74 between the dynamic seal rotating member 72 and the dynamic seal fixing member 71 is 8-10 μm. Specifically, the matching gap 74 is the gap between the outer peripheral surface of the dynamic seal rotating member 72 and the inner side wall of the groove 710 .

[0045] In this embodiment, the height difference h between the bearing surface 33 of the air-floating rotor 3 and the top surface of the dynamic seal rotating member 72 is 0.5-1 mm.

[0046] In order to facilitate the vacuum extraction of the sealed cavity, it is preferred that the first negative pressure gas circuit 15 is provided in the base 1, the second negative pressure gas circuit 711 is provided in the dynamic seal fixing member 71, and the third negative pressure gas circuit 722 is provided in the dynamic seal rotating member 72. The first negative pressure gas circuit 15, the second negative pressure gas circuit 711, and the third negative pressure gas circuit 722 are sequentially connected. The vacuum of the sealed cavity is discharged along the third negative pressure gas circuit 722, the second negative pressure gas circuit 711, and the first negative pressure gas circuit 15 in sequence, so as to form a negative pressure in the first through hole 341.

[0047] In some embodiments, the air-floating DD motor further comprises a joint seat 8, which is connected to the base 1, and is connected to an air inlet pipe joint 81, an air outlet pipe joint 82, a power line joint 83 and an encoder line joint 84. An air inlet pipe can be inserted at the air inlet pipe joint 81 to connect to the gas source so as to fill the gas into the channel 11. An air outlet pipe can be inserted at the air outlet pipe joint 82 to connect to a vacuum pump for vacuuming. By setting a power line joint 83 and an encoder line joint 84, line switching can be performed from the outside. Specifically, the air inlet pipe joint 81, the air outlet pipe joint 82, the power line joint 83 and the encoder line joint 84 are screwed to the joint seat 8, and the joint seat 8 is then screwed to the base 1.

[0048] When the present invention is in use, by blowing air into the channel 11, the gas enters the annular pipe 13, and the gas in the annular pipe 13 enters the first air channel 211, the second air channel 212 and the third air channel 213. The gas flowing out of the throttle plug 22 is respectively filled in the radial gap 52, the upper axial gap 51, and the lower axial gap 53, so that the carrier 31 is suspended, the motor rotor 42 is coupled with the motor stator 41, and the motor rotor 42 drives the carrier 31 to rotate, thereby driving the wafer on the bearing surface 33 of the carrier 31 to rotate. The gas in the space surrounded by the wafer, the carrier 31 and the dynamic seal rotating member 72 is extracted, and the gas is pumped out along the third negative pressure gas path 722, the second negative pressure gas path 711, and the first negative pressure gas path 15 to form a vacuum cavity with negative pressure, and the wafer is adsorbed by the negative pressure.

[0049] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An air-floating DD motor, characterized in that: include: A base, wherein a channel is provided in the base; An air-floating stator is fixed to the base, an air passage is provided inside the air-floating stator, and the air passage is connected to the channel; An air-floating rotor, covering the air-floating stator and being arranged in a ring outside the air-floating stator, an upper axial gap, a radial gap and a lower axial gap are formed between the air-floating rotor and the air-floating stator, and the upper axial gap, the radial gap and the lower axial gap are all connected to the air passage; A rotation drive assembly is connected to the air-floating rotor and can drive the air-floating rotor to rotate relative to the air-floating stator.

2. The air-floating DD motor according to claim 1, characterized in that: The air-floating rotor includes a carrier and a mounting seat connected to the bottom end of the carrier, an upper axial gap is formed between the carrier and the upper surface of the air-floating stator, a radial gap is formed between the carrier and the outer peripheral surface of the air-floating stator, and a lower axial gap is formed between the mounting seat and the lower surface of the air-floating stator.

3. The air-floating DD motor according to claim 2, characterized in that: The mounting seat is connected to a circular grating, and the base is connected to a reading head, and the reading head is used to read the rotation value of the circular grating.

4. The air-floating DD motor according to claim 1, characterized in that: The upper axial clearance, radial clearance and lower axial clearance are all 8-10 μm.

5. The air-floating DD motor according to claim 1, characterized in that: The rotary drive assembly comprises a motor stator and a motor rotor coupled to the motor stator. The motor stator is fixed to the base, and the motor rotor is connected to the air-floating rotor.

6. The air-floating DD motor according to claim 5, characterized in that: It also includes a shell, which is arranged outside the motor stator. The motor stator and the shell are in interference fit, and the shell and the base are in interference fit.

7. An air-floating DD motor according to any one of claims 1 to 6, characterized in that: It also includes a dynamic seal fixing part and a dynamic seal rotating part. One end of the dynamic seal fixing part along the axial direction is connected to the base, and the other end extends into the air-floating stator. One end of the dynamic seal rotating part along the axial direction is fitted in the dynamic seal fixing part, and the other end is located in the air-floating rotor and connected to the air-floating rotor. The top surface of the dynamic seal rotating part is lower than the bearing surface of the air-floating rotor. The dynamic seal fixing part is respectively connected to the base and the dynamic seal rotating part.

8. The air-floating DD motor according to claim 7, characterized in that: The bearing surface of the air-floating rotor is provided with a stepped hole, and the stepped hole includes a first through hole, a second through hole and a third through hole which are sequentially connected along the axial direction and have successively decreasing hole diameters.

9. The air-floating DD motor according to claim 7, characterized in that: The matching clearance between the dynamic seal rotating part and the dynamic seal fixed part is 8-10 μm.

10. The air-floating DD motor according to claim 7, characterized in that: The height difference between the bearing surface of the air-floating rotor and the top surface of the dynamic seal rotating member is 0.5-1 mm.

11. The air-floating DD motor according to claim 7, characterized in that: A first negative pressure air circuit is arranged in the base, a second negative pressure air circuit is arranged in the dynamic seal fixing part, and a third negative pressure air circuit is arranged in the dynamic seal rotating part. The first negative pressure air circuit, the second negative pressure air circuit and the third negative pressure air circuit are sequentially connected.

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