Workpiece cleaning apparatus and workpiece cleaning method

Abstract

To provide an apparatus and a method for cleaning a workpiece, which can reduce the amount of particles adhering to the rear surface of the workpiece.SOLUTION: In the workpiece washing device provided with a fixed body 11 having a cylindrical part 11a and a lid part 11b and a rotary body 13 storing the cylindrical part 11a therein, an exhaust port 28 provided on the lower surface of the lid part 11b, an exhaust pipe 21 connected to the exhaust port 28 and having one end connected to the exhaust port 28, a suction means 22 connected to the other end of the exhaust pipe 21 and sucking gas in a space between the fixed body 11 and the rotary body 13, an inert gas feed port 25 provided on the lower surface of the lid part 11b, an inert gas feed pipe 26 connected to the inside of the fixed body 11 and having one end connected to the inert gas feed port 25, and an inert gas feed means 27 connected to the other end of the inert gas feed pipe 21 and feeding inert gas between the fixed body 11 and the rotary body 13 are provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a workpiece cleaning device and a workpiece cleaning method. [Background technology]

[0002] Silicon wafers have traditionally been used as substrates for semiconductor devices. Silicon wafers are obtained by processing single-crystal silicon ingots grown by the Czochralski (CZ) method or other methods. During this processing, particles such as polishing powder adhere to the surface of the silicon wafer, so the silicon wafer is cleaned after processing.

[0003] There are two types of cleaning equipment for workpieces such as silicon wafers: batch-type cleaning equipment that cleans multiple workpieces simultaneously, and single-wafer-type cleaning equipment that cleans each workpiece one by one.Of these, single-wafer-type cleaning equipment has become more popular in recent years because it requires a relatively small amount of cleaning liquid, can avoid cross-contamination between workpieces, and is becoming more difficult to process multiple workpieces simultaneously due to the increasing diameter of the workpieces.

[0004] In single-wafer cleaning equipment, the workpiece to be cleaned is placed on a workpiece holder installed on a rotating table, and while the workpiece rotates at high speed together with the rotating table, cleaning liquid is sprayed onto the workpiece's front and back surfaces from upper and lower nozzles to remove particles. During the drying process after the workpiece cleaning process, the centrifugal force generated by the workpiece's high-speed rotation causes air below the center of the workpiece to flow toward the workpiece's periphery, creating negative pressure below the workpiece. As a result, particles generated by the device's drive unit and other parts are attracted to the bottom of the workpiece's center through gaps within the device, causing the problem of them adhering to the back surface of the workpiece.

[0005] Therefore, in Patent Document 1, the present applicant proposed an apparatus that reduces the amount of particles adhering to the back surface of a workpiece by providing an exhaust port for exhausting particles generated in the driving section of the apparatus and exhausting gas containing particles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-106206 Summary of the Invention [Problem to be solved by the invention]

[0007] The device described in Patent Document 1 above can significantly reduce the amount of particles adhering to the back surface of a workpiece, but in recent years, semiconductor devices have become increasingly miniaturized, and the level of cleanliness required of the workpiece has become increasingly higher.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a workpiece cleaning device and a workpiece cleaning method that can reduce the amount of particles adhering to the back surface of a workpiece. [Means for solving the problem]

[0009] The present invention, which solves the above problems, is as follows. [1] A fixed body having a first cylindrical portion extending vertically and a lid portion covering an upper portion of the first cylindrical portion; a rotating body having a cylindrical second cylindrical portion having a diameter larger than that of the first cylindrical portion of the fixed body and accommodating the first cylindrical portion therein, a rotary table arranged on top of the second cylindrical portion, and a workpiece holder arranged on the surface of the rotary table and holding a workpiece to be cleaned, the rotating body being rotatably supported by the fixed body by a pair of upper and lower bearings arranged in a gap between the first cylindrical portion of the fixed body and the rotating body; an upper nozzle that sprays a cleaning liquid toward the surface of the workpiece; a lower nozzle disposed inside the fixed body and fixed to the lid portion, for spraying a cleaning liquid toward the rear surface of the workpiece; A workpiece cleaning device including a motor that rotates the rotating body, a first exhaust port provided on the underside of the lid portion for exhausting gas in a gap between the fixed body and the rotating body from the gap; a first exhaust pipe disposed within the fixed body and connected to the first exhaust port; a suction means connected to the first exhaust pipe for suctioning gas in the gap between the fixed body and the rotating body; an inert gas supply port provided on a lower surface of the lid portion and configured to supply an inert gas between the fixed body and the rotating body; an inert gas supply pipe disposed within the fixed body, one end of which is connected to the inert gas supply port; an inert gas supply means connected to the other end of the inert gas supply pipe and supplying an inert gas between the fixed body and the rotating body; A workpiece cleaning device comprising:

[0010] [2] The workpiece cleaning device described in [1] above, further comprising a second exhaust port provided on the side of the lid portion for exhausting gas in the gap between the fixed body and the rotating body from the gap.

[0011] [3] A workpiece cleaning device according to [1] or [2], which has a labyrinth structure between the underside of the lid and the rotating body, and the inert gas supply port is provided closer to the center of the lid than the labyrinth structure.

[0012] [4] The workpiece cleaning device according to any one of [1] to [3], wherein the first exhaust port is provided closer to the center of the lid than the inert gas supply port.

[0013] [5] Further comprising a member fixed to an upper portion of the motor; the motor is provided above the rotating body, The workpiece cleaning device according to any one of [1] to [4], wherein the member has an exhaust path for exhausting gas from a space in which the motor is disposed.

[0014] [6] The workpiece cleaning device according to [5], wherein at least one of the surface of the member adjacent to the rotating body and the surface of the rotating body adjacent to the member has a labyrinth structure.

[0015] [7] A method for cleaning both surfaces of a workpiece using the workpiece cleaning device according to any one of [1] to [6], a cleaning process in which, while rotating the rotating body at a first rotation speed by the motor to rotate the workpiece, a cleaning liquid is sprayed from the upper nozzle toward the front surface of the workpiece and from the lower nozzle toward the back surface of the workpiece, thereby cleaning both surfaces of the workpiece; a drying step of rotating the rotor by the motor at a second rotation speed higher than the first rotation speed to dry the workpiece after cleaning, A method for cleaning a workpiece, characterized in that the inert gas supply means and the suction means are driven to supply the inert gas from the inert gas supply port while exhausting gas from the gap between the fixed body and the rotating body.

[0016] [8] The method for cleaning a workpiece according to [7], wherein the workpiece is a silicon wafer.

[0017] [9] The method for cleaning a workpiece according to [7] or [8], wherein the flow rate of the inert gas supplied from the inert gas supply port is equal to or less than the flow rate of the gas exhausted from the first exhaust port.

[0018]

[10] The method for cleaning a workpiece according to any one of [7] to [9], wherein the flow rate of the gas exhausted from the first exhaust port is greater than the flow rate of the gas exhausted from the second exhaust port. [Effects of the Invention]

[0019] According to the present invention, the amount of particles adhering to the back surface of the workpiece can be reduced. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing a main part of a preferred example of a workpiece cleaning device according to the present invention; [Figure 2] FIG. 2 is an enlarged view of the upper portion of the cleaning device shown in FIG. [Figure 3] FIG. 2 is an enlarged view of the vicinity of a motor of the cleaning device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] (Workpiece cleaning device) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A workpiece cleaning device according to the present invention includes a fixed body having a cylindrical first cylindrical portion extending vertically and a lid portion covering an upper portion of the first cylindrical portion, a cylindrical second cylindrical portion having a diameter larger than that of the first cylindrical portion of the fixed body and accommodating the first cylindrical portion therein, a turntable arranged on top of the second cylindrical portion, and a rotor having a workpiece holder mounted on the surface of the turntable and holding a workpiece to be cleaned, the rotor being rotatably supported on the fixed body by a pair of upper and lower bearings arranged in a gap between the first cylindrical portion of the fixed body and the rotor, an upper nozzle that sprays a cleaning liquid toward the front surface of the workpiece, a lower nozzle arranged inside the fixed body and fixed to the lid portion that sprays the cleaning liquid toward the back surface of the workpiece, and a motor that rotates the rotor. Here, the device is characterized by comprising a first exhaust port provided on the underside of the lid portion for exhausting gas in the gap between the fixed body and the rotating body from the gap, a first exhaust pipe arranged inside the fixed body and connected to the first exhaust port, suction means connected to the first exhaust pipe for sucking gas in the gap between the fixed body and the rotating body, an inert gas supply port provided on the underside of the lid portion for supplying inert gas between the fixed body and the rotating body, an inert gas supply pipe arranged inside the fixed body and one end connected to the inert gas supply port, and inert gas supply means connected to the other end of the inert gas supply pipe for supplying inert gas between the fixed body and the rotating body.

[0022] Fig. 1 shows the main parts of a preferred example of a workpiece cleaning apparatus according to the present invention. Fig. 2 shows an enlarged view of the upper part of the apparatus shown in Fig. 1. In the workpiece cleaning apparatus 1 shown in Fig. 1, a fixed body 11 has a first cylindrical portion 11a that extends vertically and a lid portion 11b that covers the upper part of the first cylindrical portion 11a. The lid portion 11b holds a lower nozzle 19, which will be described later. The fixed body 11 is fixed to a floor portion (not shown) and forms a main column that supports a rotor 13.

[0023] The rotating body 13 has a cylindrical second cylindrical portion 13a having a larger diameter than the first cylindrical portion 11a of the fixed body 11, a rotating table 13b arranged on the upper part of the second cylindrical portion 13a, and a workpiece holder 13c provided on the surface of the rotating table 13b and holding the workpiece W to be cleaned. In the illustrated example, the rotating table 13b is provided with a recess 13d, and the lid portion 11b of the fixed body 11 is housed in this recess 13d.

[0024] The second cylindrical portion 13a accommodates the fixed body 11 therein. A pair of upper and lower bearings 14 are disposed in the gap between the first cylindrical portion 11a of the fixed body 11 and the rotating body 13. In this way, the rotating body 13 is rotatably supported by the fixed body 11 via the bearings 14.

[0025] Further, a motor 16 is provided in the second cylindrical portion 13a of the rotating body 13, and is configured so that the second cylindrical portion 13a and, in turn, the workpiece W on the rotary table 13b are rotated by the driving of the motor 16. As shown in Fig. 1, the motor 16 is provided directly in the second cylindrical portion 13a without a belt or the like (i.e., the motor 16 is configured to directly rotate the rotating body 13), and is preferably provided at the top of the second cylindrical portion 13a. As the motor 16, for example, a spindle motor can be used.

[0026] Preferably, a member 17 is provided that is fixed to the upper portion of the motor 16 and has an exhaust path 17a for exhausting gas from the space in which the motor 16 is disposed. A gap exists between the member 17 and the rotor 13, and particles generated by dust generation in the motor 16 may pass outside the rotor 13 and reach the back surface of the workpiece W. Therefore, as shown in FIG. 3, a labyrinth structure 17b may be provided on the surface of the member 17 adjacent to the rotor 13. This prevents particles generated by dust generation in the motor 16 from passing outside the rotor 13 and reaching the back surface of the workpiece W. The labyrinth structure 17b may be provided on the surface of the rotor 13 adjacent to the member 17, or on both the member 17 and the rotor 13. While FIG. 1 illustrates an L-shaped exhaust path 17a provided on the member 17, this is not limited thereto and the exhaust path 17a may also be provided in the gap between the fixed body 11 and the rotor 13. The exhaust path 17a is connected to an exhaust pipe (second exhaust pipe) 30.

[0027] Meanwhile, upper nozzles 18 are provided on the top of the cleaning device 1 to spray cleaning liquid toward the surface (front side) of the workpiece W. The number of upper nozzles 18 is the same as the number of types of chemical liquid, and for example, when spraying four types of chemical liquid, the upper nozzles 18 can be configured with four nozzles arranged at equal intervals.

[0028] Furthermore, the lid portion 11b of the stationary body 11 holds a lower nozzle 19 that sprays the cleaning liquid toward the back surface of the workpiece W, and is arranged so that the cleaning liquid can be sprayed toward the center of the back surface of the workpiece W. As with the upper nozzles 18, the lower nozzles 19 are prepared for each type of chemical liquid, and for example, when spraying four types of chemical liquid, the lower nozzles 19 can be composed of four nozzles arranged at equal intervals.

[0029] In the cleaning device 1 of the present invention, an exhaust port (first exhaust port) 28 for exhausting gas from the gap between the fixed body 11 and the rotor 13 is provided on the underside of the lid portion 11b. An exhaust pipe 21 arranged inside the fixed body 11 is connected to this exhaust port 28. In addition, a suction means 22 is connected to the exhaust pipe (first exhaust pipe) 21. The suction means 22 can be configured by a suction pump, a gas ejector, a water ejector, a steam ejector, or the like.

[0030] Therefore, by driving the suction means 22 while the workpiece W is being washed, the gas in the gap between the fixed body 11 and the rotating body 13, through which dust particles from dust sources such as the bearing 14 flow, can be sucked in, thereby suppressing the dust particles from reaching the back surface of the workpiece W.

[0031] It is preferable that the exhaust pipe 21 is not made of metal, but is made of a fluorine-based resin such as tetrafluoroethylene (PFA) that has high chemical resistance.

[0032] The first exhaust port 28 is provided at a position higher than the upper bearing 14. Therefore, compared to when the first exhaust port 28 is provided in the fixed body 11 directly above the upper bearing 14, more dust particles flowing through the gap between the first cylindrical portion 11a of the fixed body 11 and the second cylindrical portion 13a of the rotating body 13 can be removed.

[0033] 1, an exhaust port (second exhaust port) 20 is also provided on the side of the lid portion 11b, and is preferably connected to an exhaust pipe 21. This makes it possible to remove dust particles that are generated from the motor 16, pulleys (not shown), etc. and pass between the fixed body 11 and the rotating body 13 due to turbulence generated on the outer periphery of the device 1, as well as mist of cleaning liquid present in the space below the workpiece W.

[0034] It is preferable that four or more exhaust ports 20 are provided at equal intervals in the circumferential direction at the same height position, so that dust can be removed uniformly during cleaning.

[0035] Furthermore, the cleaning apparatus 1 of the present invention is provided with an inert gas supply port 25 provided on the underside of the lid portion 11b for supplying an inert gas between the fixed body 11 and the rotor 13. Also provided are an inert gas supply pipe 26 disposed within the fixed body 11 and having one end connected to the inert gas supply port 25, and an inert gas supply means 27 connected to the other end of the inert gas supply pipe 26 for supplying an inert gas between the fixed body 11 and the rotor 13. An air compressor or the like can be used as the inert gas supply means 27.

[0036] Therefore, by supplying an inert gas such as nitrogen gas from the inert gas supply means 27 while cleaning the workpiece W, the inert gas is supplied from the inert gas supply port 25 to the gap between the fixed body 11 and the rotating body 13, thereby preventing particles present in the gap from reaching the back surface of the workpiece W.

[0037] The first exhaust port 28 is preferably provided closer to the center of the lid portion 11b than the inert gas supply port 25. As a result, by supplying an inert gas from the inert gas supply means 27 at an appropriate flow rate while cleaning the workpiece W, a flow of inert gas is formed in the opposite direction to the flow of gas containing particles generated from the bearing 14, and the gas containing particles can be exhausted from the first exhaust port 28. The appropriate flow rate can be determined by gas analysis simulation or the like.

[0038] It is also preferable to provide a labyrinth structure (not shown) between the underside of the lid portion 11b and the rotor 13, and to provide the inert gas supply port 25 closer to the center of the lid portion 11b than the labyrinth structure. This makes it possible to prevent particles from reaching below the workpiece W, even if the particles pass below the inert gas supply port 25.

[0039] On the outer periphery of the fixed body 11 and the rotating body 13, there are provided a water receiving cover 23 to prevent the cleaning liquid that splashes in the direction of the outer periphery of the workpiece during cleaning from splashing outside the device 1, and a water receiving cup 24 to receive the cleaning liquid.

[0040] By cleaning the workpiece W using such a cleaning apparatus 1, it is possible to reduce the amount of particles adhering to the rear surface of the workpiece W after cleaning. If the amount of particles adhering to the rear surface of the workpiece W can be reduced, it is possible to improve the yield when manufacturing the workpiece W and the yield when manufacturing devices from the workpiece W (e.g., wafers).

[0041] The above-mentioned improvement in yield increases the manufacturing efficiency of semiconductor products, enabling the production of higher quality products in greater quantities, promoting technological innovation and contributing to the sustainable development of the industry. Furthermore, improved yield reduces the waste of materials consumed in the semiconductor manufacturing process, contributing to the efficient use of resources. Furthermore, improved yield reduces the waste of energy consumed in the semiconductor manufacturing process, thereby contributing to the reduction of greenhouse gas emissions.

[0042] In other words, the present invention can contribute to, for example, "Goal 9: Industry, innovation and infrastructure," "Goal 12: Ensure sustainable consumption and production," and "Goal 13: Climate change action" in the Sustainable Development Goals (SDGs).

[0043] (Workpiece cleaning method) The method for cleaning a workpiece according to the present invention is a method for cleaning both sides of a workpiece using the above-described workpiece cleaning device according to the present invention, and includes a cleaning step in which, while rotating the rotating body 13 at a first rotational speed by the motor 16 to rotate the workpiece W, a cleaning liquid is sprayed from the upper nozzle 18 toward the front side of the workpiece W and the cleaning liquid is sprayed from the lower nozzle 19 toward the back side of the workpiece W to clean both sides of the workpiece W, and a drying step in which, while rotating the rotating body 13 by the motor 16 at a second rotational speed higher than the first rotational speed, the workpiece W after cleaning is dried. Here, the drying step is characterized in that the inert gas supply means 27 and the suction means 22 are driven to supply inert gas from the inert gas supply port 25, while evacuating the gas in the gap between the fixed body 11 and the rotating body 13.

[0044] As described above, the workpiece cleaning device 1 according to the present invention can remove dust from dust sources such as the bearing 14, and reduce the amount of particles adhering to the back surface of the workpiece W after cleaning.

[0045] As described above, the method for cleaning a workpiece according to the present invention is characterized in that, during cleaning, an inert gas is supplied from an inert gas supply line to a space through which dust particles flow, while the dust particles are removed from the dust source by an exhaust line. There are no particular restrictions on the specific cleaning conditions, and the cleaning can be performed under conditions as needed.

[0046] For example, when cleaning a silicon wafer, the silicon wafer is placed on workpiece holder 13c on turntable 13b with the surface on which devices will be formed facing upward, as shown in Figure 1. Next, motor 16 is driven to rotate turntable 13b via second cylindrical portion 13a at a rotational speed of, for example, 100 to 2000 rpm. In this state, cleaning liquid is sprayed from upper nozzle 18 and lower nozzle 19 toward the front and back surfaces of the silicon wafer, respectively.

[0047] The cleaning liquid to be used is not particularly limited, and an appropriate cleaning liquid can be used depending on the purpose. For example, ozone water, hydrofluoric acid solution, ammonia hydrogen peroxide solution, etc. can be used as the cleaning liquid.

[0048] On the front surface of the silicon wafer, the cleaning solution that has adhered to the front surface (front side) of the silicon wafer due to gravity is caused to flow toward the periphery of the silicon wafer by centrifugal force, spreading the cleaning solution over the entire surface. On the back side, the cleaning solution that has adhered to the silicon wafer due to surface tension is also spread over the entire surface by centrifugal force. In this way, both the front and back surfaces of the silicon wafer can be cleaned (cleaning process).

[0049] Next, the turntable 13b is rotated at an even higher speed, and the suction means 22 is driven to start exhausting while the inert gas is supplied from the inert gas supply port 25 by the inert gas supply means 27, thereby drying the silicon wafer (drying step). After drying is completed, the turntable 13b is decelerated, and when the turntable 13 stops, the drive of the inert gas supply means 27 and the suction means 22 is stopped.

[0050] Depending on the cleaning liquid used, after the spin cleaning with the cleaning liquid, a rinse process may be performed by spraying ultrapure water or ozone water from the upper nozzle 18 and the lower nozzle 19 to remove the cleaning liquid remaining on the front and back surfaces of the silicon wafer.

[0051] In the above process, the cleaning liquid or ultrapure water that flows down from the silicon wafer or is blown off by centrifugal force is received by the water receiving cover 23 and the water receiving cup 24, and is discharged from the drain pipe 24a. In this way, the silicon wafer can be cleaned.

[0052] There are no limitations on the workpiece W to be cleaned, but silicon wafers can be suitably cleaned.

[0053] The flow rate of the inert gas supplied from the inert gas supply port 25 is preferably equal to or lower than the flow rate of the gas exhausted from the first exhaust port 28. By increasing the flow rate of the gas exhausted from the first exhaust port 28, the inert gas flows below the lid portion 11b, blocking dust particles from sliding parts (such as the bearings 14) rising from below the fixed body 11 (rotating body 13) while being exhausted from the first exhaust port 28. Furthermore, by making the flow rate of the inert gas lower than the flow rate of the gas exhausted from the first exhaust port 28, the amount of gas exhausted from the labyrinth structure located radially outward from the first exhaust port 28 can be reduced. This further reduces dust particles contained in the gas flowing from the side of the lid portion 11b toward above the lid portion 11b and ultimately toward the workpiece W.

[0054] Furthermore, it is preferable that the flow rate of the gas exhausted from the first exhaust port 28 is greater than the flow rate of the gas exhausted from the second exhaust port 20. This allows the gas to be directed toward the first exhaust port 28, which is farther from the workpiece W than the second exhaust port 20, and prevents dust particles from being directed toward the workpiece W. [Example]

[0055] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0056] (Example of invention) Silicon wafers were cleaned using the workpiece cleaning apparatus 1 shown in FIG. 1. First, in the cleaning process, the silicon wafer was rotated at a speed of 300-500 rpm, and an oxidation cleaning process using ozone water and an acid cleaning process using a hydrofluoric acid solution were repeated multiple times, followed by a rinsing process using ozone water. In the drying process, the silicon wafer was rotated at a speed of 1000-2000 rpm for spin drying. During the above cleaning and drying processes, the suction means 22 was driven around the time of completion of the cleaning process to start exhausting from the first exhaust port 28, the second exhaust port 20, and the exhaust path 17b, and nitrogen gas was supplied from the inert gas supply port 25 by the inert gas supply means 27 at a flow rate of 5-10 L / min. The above cleaning was performed on four silicon wafers.

[0057] After the drying process, the number of particles adhering to the backside of each of the four silicon wafers was measured using a particle measuring instrument (KLA-Tencor: Surfscan SP7). As a result, the number of particles per wafer was found to be 1.0.

[0058] (Conventional Example 1) Silicon wafers were cleaned in the same manner as in the invention example. However, exhaust was not performed from the first exhaust port 28, the second exhaust port 20, or the exhaust path 17b, and nitrogen gas was not supplied from the inert gas supply port 25. All other conditions were the same as in the invention example. As a result, the number of particles adhering to the backside of the wafer after the drying process was 73.3.

[0059] (Conventional example 2) Silicon wafers were cleaned in the same manner as in the invention example. However, exhaust was not performed from the first exhaust port 28 and exhaust path 17b, and nitrogen gas was not supplied from the inert gas supply port 25. All other conditions were the same as in the invention example. As a result, the number of particles adhering to the backside of the wafer after the drying process was 3.3. [Industrial Applicability]

[0060] According to the present invention, the amount of particles adhering to the back surface of the workpiece can be reduced. [Explanation of symbols]

[0061] 1 Workpiece cleaning device 11 Fixed body 11a First cylindrical portion 11b Lid 13 Rotating body 13a second cylindrical portion 13b Rotary table 13c Work holder 13d recess 14 Bearings 16 motors 17 Components 17a Exhaust route 18 Upper nozzle 19 Lower nozzle 20 Second exhaust port 21 Exhaust pipe 22 Suction means 23 Water tray cover 24 Water cup 24a Drainage tube 24b First exhaust pipe 25 Inert gas supply port 26 Inert gas supply pipe 27 Inert gas supply means 28 First exhaust port 30 Second exhaust pipe double work

Claims

1. a fixed body having a first cylindrical portion extending in a vertical direction and a lid portion covering an upper portion of the first cylindrical portion; a rotating body having a cylindrical second cylindrical portion having a diameter larger than that of the first cylindrical portion of the fixed body and accommodating the first cylindrical portion therein, a rotary table disposed on an upper portion of the second cylindrical portion, and a workpiece holder disposed on a surface of the rotary table and holding a workpiece to be cleaned, the rotating body being rotatably supported by the fixed body by a pair of upper and lower bearings disposed in a gap between the first cylindrical portion of the fixed body and the rotating body; an upper nozzle that sprays a cleaning liquid toward the surface of the workpiece; a lower nozzle disposed inside the fixed body and fixed to the lid portion, for spraying a cleaning liquid toward the rear surface of the workpiece; A workpiece cleaning device including a motor that rotates the rotating body, a first exhaust port provided on a lower surface of the lid portion for exhausting gas in a gap between the fixed body and the rotating body from the gap; a first exhaust pipe disposed within the fixed body and connected to the first exhaust port; a suction means connected to the first exhaust pipe for suctioning gas in the gap between the fixed body and the rotating body; an inert gas supply port provided on a lower surface of the lid portion and configured to supply an inert gas between the fixed body and the rotating body; an inert gas supply pipe disposed within the fixed body, one end of which is connected to the inert gas supply port; an inert gas supply means connected to the other end of the inert gas supply pipe and supplying an inert gas between the fixed body and the rotating body; A workpiece cleaning device comprising:

2. The workpiece cleaning device according to claim 1 , further comprising a second exhaust port provided on a side surface of the lid portion for exhausting gas in a gap between the fixed body and the rotating body from the gap.

3. 3. The workpiece cleaning device according to claim 1, wherein a labyrinth structure is formed between the lower surface of the lid portion and the rotating body, and the inert gas supply port is provided closer to the center of the lid portion than the labyrinth structure.

4. The workpiece cleaning device according to claim 1 or 2, wherein the first exhaust port is provided closer to the center of the lid than the inert gas supply port.

5. Further, a member fixed to an upper portion of the motor is provided. the motor is provided on the upper part of the rotating body, The workpiece cleaning device according to claim 1 or 2, wherein the member has an exhaust path for exhausting gas from a space in which the motor is disposed.

6. The apparatus for cleaning a workpiece according to claim 5 , wherein at least one of a surface of the member adjacent to the rotating body and a surface of the rotating body adjacent to the member has a labyrinth structure.

7. A method for cleaning both surfaces of a workpiece using the workpiece cleaning device according to claim 1 or 2, comprising: a cleaning process in which, while rotating the rotating body at a first rotation speed by the motor to rotate the workpiece, a cleaning liquid is sprayed from the upper nozzle toward the front surface of the workpiece and from the lower nozzle toward the back surface of the workpiece, thereby cleaning both surfaces of the workpiece; a drying step of rotating the rotor by the motor at a second rotation speed higher than the first rotation speed to dry the workpiece after cleaning, A method for cleaning a workpiece, characterized in that the inert gas supply means and the suction means are driven to supply the inert gas from the inert gas supply port while exhausting gas from the gap between the fixed body and the rotating body.

8. 8. The method for cleaning a workpiece according to claim 7, wherein the workpiece is a silicon wafer.

9. 8. The method for cleaning a workpiece according to claim 7, wherein a flow rate of the inert gas supplied from the inert gas supply port is equal to or less than a flow rate of the gas exhausted from the first exhaust port.

10. 8. The method for cleaning a workpiece according to claim 7, wherein a flow rate of the gas exhausted from the first exhaust port is greater than a flow rate of the gas exhausted from the second exhaust port.

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