A cleaning rack capable of rotating silicon wafers and a silicon wafer cleaning device using the cleaning rack

Abstract

The invention discloses a cleaning rack capable of rotating silicon wafers. A silicon wafer cleaning device using the cleaning rack comprises a rack body, a driving motor, and a silicon wafer basket; the rack body comprises a longitudinally arranged top rack, a vertically arranged connecting pipe with an inner hole, and a longitudinally arranged silicon wafer basket rack, and a bottom plate is arranged at the bottom end of the connecting pipe; the cross section of the inner hole of the connecting pipe is rectangular; two parallel rotating rods are longitudinally arranged on the silicon wafer basket rack, and rotating rod mounting holes are longitudinally arranged at the left and right ends of the front side surface of the bottom end of the connecting pipe, and two rotating rods are inserted into a rotating rod mounting hole respectively; a sprocket is arranged in the inner hole of the connecting pipe of each rotating rod, and the two sprockets are connected by a second transmission chain, and the plane where the second transmission chain is located is perpendicular to the two rotating rods; a silicon wafer basket is installed on the silicon wafer basket rack. The device of the invention can place silicon wafers of different sizes in the silicon wafer basket for rotational cleaning, and is particularly suitable for cleaning small batches of silicon wafers of multiple sizes.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor silicon wafer cleaning, and relates to a cleaning rack capable of rotating silicon wafers and a silicon wafer cleaning device using the cleaning rack. Background Art

[0002] In the production of semiconductor devices, about 20% of the processes are related to silicon wafer cleaning. After slicing, chamfering, grinding, surface treatment, polishing, epitaxy and other processes, the surface of the silicon wafer has been seriously contaminated. The purpose of cleaning is to remove contamination such as particles, metal ions and organic matter on the surface of the silicon wafer.

[0003] At present, silicon wafer cleaning is mainly based on chemical cleaning, which refers to the process of using various chemical reagents and organic solvents to react or dissolve impurities and oils adsorbed on the surface of the object to be cleaned, or accompanied by physical measures such as ultrasound, heating, and vacuuming, so that impurities are desorbed from the surface of the object to be cleaned, and then rinsed with a large amount of high-purity hot and cold deionized water to obtain a clean surface. Chemical cleaning can be divided into wet chemical cleaning and dry chemical cleaning, among which wet chemical cleaning technology still occupies a dominant position in silicon wafer surface cleaning.

[0004] When the cleaning liquid contacts the silicon wafer, there is a very thin water film on the surface of the silicon wafer. Due to the intermolecular attraction, this water film is stationary relative to the silicon wafer, also known as the boundary layer. The existence of the boundary layer has a very important influence on the cleaning effect of the silicon wafer. For particles with a diameter smaller than the thickness of the boundary layer, they can only rely on themselves to slowly diffuse through the boundary layer, enter the water flow, and then be carried away from the surface of the silicon wafer by the water flow. These particles are difficult to remove during the cleaning process. The thickness of the boundary layer depends on the viscosity of the liquid, the relative speed between the liquid and the silicon wafer surface, etc. Reducing the thickness of the boundary layer has become an important challenge to improve cleaning efficiency.

[0005] In wet chemical cleaning, a cleaning basket is needed to hold silicon wafers, and then the cleaning basket is placed in the cleaning liquid. Existing cleaning baskets are fixed after being placed in the cleaning liquid. In order to reduce the thickness of the boundary layer, the water flow rate can only be increased, which requires continuous increase in equipment power, resulting in a large loss of electricity. In addition, there is also the problem that the cleaning liquid of chemical cleaning seriously corrodes the drive device, resulting in a relatively short life of the drive device, and the problem of poor versatility in cleaning large batches of silicon wafers of different sizes. Summary of the invention

[0006] The object of the present invention is to provide a cleaning rack capable of rotating silicon wafers and a silicon wafer cleaning device using the cleaning rack, in view of the deficiencies of the prior art.

[0007] The technical solution adopted by the present invention is as follows.

[0008] A cleaning rack capable of rotating silicon wafers, characterized in that it comprises a rack body, a driving motor, and a silicon wafer basket; the rack body comprises a longitudinally arranged top rack, a vertically arranged connecting pipe with an inner hole, and a longitudinally arranged silicon wafer basket rack, the bottom end of the connecting pipe is connected to the rear end of the silicon wafer basket rack, the top end of the connecting pipe is connected to the top rack, the driving motor is arranged directly above the connecting pipe on the top rack; a bottom plate is arranged at the bottom end of the connecting pipe; the cross section of the inner hole of the connecting pipe is rectangular.

[0009] Two parallel rotating rods are longitudinally arranged on the silicon wafer flower basket frame, and rotating rod mounting holes are longitudinally arranged at the left and right ends of the front side surface of the bottom end of the connecting tube, and the two rotating rods are respectively inserted into a rotating rod mounting hole; a sprocket is arranged in the inner hole of the connecting tube of each rotating rod, and the two sprockets are connected by a second transmission chain, and the plane where the second transmission chain is located is perpendicular to the two rotating rods.

[0010] The rear end of the driving motor is provided with a driving wheel. Among the two rotating rods, a passive wheel is provided in the inner hole of the connecting pipe of one of the rotating rods. The driving motor is provided with a driving wheel, and the planes where the driving wheel and the passive wheel are located are perpendicular to the two rotating rods.

[0011] The driving wheel and the driven wheel are connected through a first transmission chain; the lower end of the first transmission chain is located in the inner hole of the connecting pipe.

[0012] A first sealing sleeve is provided between each rotating rod and the inner hole of the connecting pipe;

[0013] A partition perpendicular to the two rotating rods is arranged just above the front side of the connecting pipe of the top frame, a first cavity is arranged on the rear side of the partition on the top frame, and a second cavity is arranged on the front side of the partition on the top frame; the top end of the connecting pipe is connected to the bottom of the first cavity.

[0014] A motor shaft mounting hole perpendicular to the partition is provided on the partition, and the drive motor is installed in the second cavity; a drive shaft is longitudinally provided on the drive motor, and the drive shaft of the drive motor passes through the motor shaft mounting hole, and the driving wheel is installed on the drive shaft and located in the first cavity; the upper end of the first transmission chain is located in the first cavity; a second sealing sleeve is provided between the motor shaft mounting hole and the drive shaft of the drive motor.

[0015] A silicon wafer basket is installed on the silicon wafer basket frame. The silicon wafer basket is provided with a plurality of silicon wafer slots perpendicular to the two silicon wafers and the two rotating rods. When a plurality of round silicon wafers are placed on the silicon wafer slots in the silicon wafer basket, the bottom end of each silicon wafer contacts the radial outer peripheral surface of the two rotating rods.

[0016] As an optimal technical solution, the silicon wafer flower basket includes a left frame plate and a right frame plate, and the front end of the left frame plate and the front end of the right frame plate, and the rear end of the left frame plate and the rear end of the right frame plate are connected by a connecting plate; a number of silicon wafer slots are respectively provided on the left frame plate and the right frame plate; the bottom surfaces of the left frame plate and the right frame plate are flush and located below the bottom surface of the connecting plate.

[0017] As a preferred technical solution, the long side of the inner hole cross section of the connecting pipe is arranged horizontally.

[0018] As a preferred technical solution, a rubber sleeve is provided on the radial outer peripheral surface of each rotating roller outside the connecting tube. The rubber sleeve will not damage the silicon wafer.

[0019] As a preferred technical solution, a glass door is provided at the top of the second cavity. The glass door is provided to facilitate observation of the motor status.

[0020] As a preferred technical solution, a plurality of ventilation holes are provided on the front side of the first cavity on the top frame.

[0021] A silicon wafer cleaning device comprises a cleaning device frame, a lifting device, any one of the above cleaning frames capable of rotating silicon wafers, and a cleaning tank, wherein the rear end of the top frame of the cleaning frame capable of rotating silicon wafers is installed on the lifting device, the lifting device is installed on the cleaning device frame, and the cleaning tank is installed directly below the silicon wafer basket frame of the cleaning device frame.

[0022] As a preferred technical solution, the lifting device is an electric linear drive.

[0023] As a preferred technical solution, the silicon wafer flower basket rack is provided with a silicon wafer flower basket slot opening upward, and the silicon wafer flower basket is inserted into the silicon wafer flower basket slot.

[0024] The silicon wafer cleaning device comprises a rotatable ring-shaped conveying device with a horizontal top surface, the rotatable ring-shaped conveying device is connected to a plurality of lifting devices, the bottom end of the lifting devices is connected to any one of the above-mentioned cleaning racks that can rotate the silicon wafers, and some of the cleaning racks that can rotate the silicon wafers are provided with cleaning tanks below, which has the advantage of enabling flow operation.

[0025] The beneficial effects of the cleaning rack capable of rotating silicon wafers of the present invention are as follows: under the action of a driving motor, the silicon wafers can be rotated in the silicon wafer basket, and when the silicon wafer basket enters the cleaning tank, the cleaning liquid and the silicon wafer move relative to each other, and the cleaning is relatively thorough; the driving device of the rotating roller is located in the inner hole of the connecting pipe, the first sealing sleeve prevents the cleaning liquid from entering the connecting pipe, and the partition plate and the second sealing sleeve prevent the volatile components of the cleaning liquid from entering the second cavity, thereby prolonging the service life of the driving motor; the silicon wafer basket rack is longitudinally arranged at the bottom end of the connecting pipe, with a large operating space, and the installation is completed by inserting the silicon wafer basket into the silicon wafer basket slot, and after the cleaning is completed, the silicon wafer basket can be pulled out of the silicon wafer basket slot, and the installation of the silicon wafer basket is convenient; the two rotating rollers are located at the bottom end of the silicon wafer basket, and silicon wafers of different sizes can be placed in the silicon wafer basket, and all of them can be rotated for cleaning, and are particularly suitable for cleaning small batches of silicon wafers of various sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a three-dimensional structural schematic diagram of a preferred embodiment of the cleaning rack capable of rotating silicon wafers of the present invention.

[0027] Figure 2 yes Figure 1 A partial enlarged view of part B.

[0028] Figure 3 yes Figure 1 A partial enlarged view of part C.

[0029] Figure 4 yes Figure 3 A partial enlarged view of part D.

[0030] Figure 5 yes Figure 3 A partial enlarged view of part E.

[0031] Figure 6 yes Figure 1 A cross-sectional view along line AA' of a cleaning rack capable of rotating silicon wafers is shown.

[0032] Figure 7 yes Figure 6 A partial enlarged view of part F.

[0033] Figure 8 yes Figure 1 Right side view of the cleaning rack that allows the silicon wafer to rotate.

[0034] Fig. 9 yes Figure 1 A front view of a cleaning rack that allows silicon wafers to rotate is shown.

[0035] Fig.10 yes Fig. 9 A cross-sectional view along G-G' of a cleaning rack capable of rotating silicon wafers is shown.

[0036] Fig.11 yes Fig.10 A partial enlarged view of part I.

[0037] Fig.12 yes Fig.10 A partial enlarged view of part H.

[0038] Fig.13 yes Fig.12 A partial enlarged view of part J.

[0039] Fig.14 yes Figure 1 The diagram shows the use status of the cleaning rack that can rotate silicon wafers.

[0040] Fig.15 yes Fig.14 A partial enlarged view of part K.

[0041] Fig.16 It is a structural schematic diagram of a preferred embodiment of a silicon wafer cleaning device.

[0042] Fig.17 yes Fig.16 A state diagram of a silicon wafer cleaning device is shown.

[0043] Fig.18 It is a structural schematic diagram of a preferred embodiment of a silicon wafer cleaning device.

[0044] Silicon wafer basket frame-1; driving motor-2; ventilation hole-3; rotating rod-4; second transmission chain-5; first transmission chain-6; silicon wafer basket-7; silicon wafer-8; top frame-9; connecting pipe-10; bottom plate-11;

[0045] Sprocket-12; driving wheel-13; driven wheel-14; inner hole-15; first sealing sleeve-16;

[0046] Partition-17; first cavity-18; second cavity-19; drive shaft-20; second sealing sleeve-21; silicon wafer slot-22;

[0047] Left frame plate-23; right frame plate-24; connecting plate-25;

[0048] Rubber sleeve-26; glass door-27; cleaning tank-28; lifting device-29; cleaning device frame-30; rotatable ring-shaped conveying device-31. DETAILED DESCRIPTION

[0049] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0050] Example 1. Figure 1-17 As shown, a cleaning rack capable of rotating silicon wafers is characterized in that it includes a rack body, a driving motor 2, and a silicon wafer basket 7; the rack body includes a longitudinally arranged top frame 9, a vertically arranged connecting pipe 10 with an inner hole 15, and a longitudinally arranged silicon wafer basket frame 1, the bottom end of the connecting pipe 10 is connected to the rear end of the silicon wafer basket frame 1, the top end of the connecting pipe 10 is connected to the top frame 9, the driving motor 2 is arranged on the top frame 9 directly above the connecting pipe 10; a bottom plate 11 is provided at the bottom end of the connecting pipe 10; the cross section of the inner hole 15 of the connecting pipe 10 is rectangular.

[0051] Two parallel rotating rods 4 are longitudinally arranged on the silicon wafer flower basket frame 1, and rotating rod mounting holes are longitudinally arranged at the left and right ends of the front side surface of the bottom end of the connecting tube 10, and the two rotating rods 4 are respectively inserted into a rotating rod mounting hole; a sprocket 12 is arranged in the inner hole 15 of the connecting tube 10 of each rotating rod 4, and the two sprockets 12 are connected by a second transmission chain 5, and the plane where the second transmission chain 5 is located is perpendicular to the two rotating rods 4.

[0052] The rear end of the driving motor 2 is provided with a driving wheel 13. Among the two rotating rods 4, a driven wheel 14 is provided in the inner hole 15 of the connecting pipe 10 of one of the rotating rods 4. The driving motor 2 is provided with a driving wheel 13, and the plane where the driving wheel 13 and the driven wheel 14 are located is perpendicular to the two rotating rods 4.

[0053] The driving wheel 13 is connected to the driven wheel via a first transmission chain 6 ; the lower end of the first transmission chain 6 is located in the inner hole 15 of the connecting pipe 10 .

[0054] A first sealing sleeve 16 is provided between each rotating rod 4 and the inner hole 15 of the connecting tube 10;

[0055] A partition 17 perpendicular to the two rotating rods 4 is provided directly above the front side of the connecting tube 10 of the top frame 9, a first cavity 18 is provided on the rear side of the partition 17 on the top frame 9, and a second cavity 19 is provided on the front side of the partition 17 on the top frame 9; the top end of the connecting tube 10 is connected to the bottom of the first cavity 18.

[0056] A motor shaft mounting hole perpendicular to the partition 17 is provided on the partition 17, and the drive motor 2 is installed in the second cavity 19; a drive shaft 20 is longitudinally provided on the drive motor 2, and the drive shaft 20 of the drive motor 2 passes through the motor shaft mounting hole, and the driving wheel 13 is installed on the drive shaft 20 and is located in the first cavity 18; the upper end of the first transmission chain 6 is located in the first cavity 18; a second sealing sleeve 21 is provided between the motor shaft mounting hole and the drive shaft 20 of the drive motor 2.

[0057] A silicon wafer basket 7 is installed on the silicon wafer basket rack 1. The silicon wafer basket 7 is provided with a plurality of silicon wafer slots 22 perpendicular to the two silicon wafers and the two rotating rods 4. When a plurality of round silicon wafers 8 are placed on the silicon wafer slots 22 in the silicon wafer basket 7, the bottom end of each silicon wafer 8 contacts the radial outer peripheral surface of the two rotating rods 4.

[0058] The silicon wafer basket 7 includes a left frame plate 23 and a right frame plate 24. The front end of the left frame plate 23 and the front end of the right frame plate 24, and the rear end of the left frame plate 23 and the rear end of the right frame plate 24 are connected by a connecting plate 25. A plurality of silicon wafer slots 22 are respectively provided on the left frame plate 23 and the right frame plate 24. The bottom surfaces of the left frame plate 23 and the right frame plate 24 are flush and located below the bottom surface of the connecting plate 25.

[0059] The long side of the cross section of the inner hole 15 of the connecting pipe 10 is arranged in the transverse direction.

[0060] The radially outer peripheral surface of the portion other than the connecting tube 10 of each rotating roller 4 is provided with a rubber sleeve 26. The rubber sleeve is provided so as not to damage the silicon wafer.

[0061] A glass door 27 is provided at the top of the second cavity 19. The glass door is provided to facilitate observation of the motor status.

[0062] A plurality of ventilation holes 3 are provided on the front side of the first cavity 18 on the top frame 9 .

[0063] The silicon wafer cleaning device comprises a cleaning device frame 30, a lifting device 29, any one of the above-mentioned cleaning frames capable of rotating silicon wafers, and a cleaning tank 28. The rear end of the top frame 9 of the cleaning frame capable of rotating silicon wafers is installed on the lifting device 29, the lifting device 29 is installed on the cleaning device frame 30, and the cleaning tank 28 is installed directly below the silicon wafer basket frame 1 of the cleaning device frame 30.

[0064] The lifting device 29 is an electric linear drive.

[0065] The silicon wafer basket frame 1 is provided with a silicon wafer basket slot 32 which opens upward, and the silicon wafer basket 7 is inserted into the silicon wafer basket slot 32 .

[0066] Under the action of the driving motor 2, the silicon wafer 8 can be rotated in the silicon wafer basket 7. When the silicon wafer basket 7 enters the cleaning tank, the cleaning liquid and the silicon wafer move relative to each other, and the cleaning is relatively thorough. The driving device of the rotating roller 4 is located in the inner hole 15 of the connecting tube 10. The existence of the first sealing sleeve 16 prevents the cleaning liquid from entering the connecting tube 10. The partition 17 and the second sealing sleeve 21 prevent the volatile components of the cleaning liquid from entering the second cavity 19, thereby extending the service life of the driving motor 2. The silicon wafer basket frame 1 is longitudinally arranged at the bottom of the connecting tube 10, with a large operating space. The installation is completed by inserting the silicon wafer basket 7 into the silicon wafer basket slot 32. After cleaning, the silicon wafer basket 7 can be pulled out of the silicon wafer basket slot 32, and the installation of the silicon wafer basket 7 is convenient. The two rotating rollers 4 are located at the bottom of the silicon wafer basket 7. Silicon wafers of different sizes can be placed in the silicon wafer basket 7, and all of them can be rotated for cleaning, which is particularly suitable for cleaning small batches of silicon wafers of various sizes.

[0067] Example 2. Fig.18 As shown, the difference between this embodiment and embodiment 1 is that the silicon wafer cleaning device includes a rotatable ring-shaped conveying device 31 with a horizontal top surface, and four lifting devices 29 are connected to the rotatable ring-shaped conveying device. The bottom end of the lifting device 29 is connected to the cleaning rack that can rotate the silicon wafers described in embodiment 1, and a cleaning tank 28 is provided under each of the two cleaning racks that can rotate the silicon wafers. The advantage is that it can be operated in an assembly line.

[0068] The above-mentioned embodiments are only for understanding the present invention, and are not intended to limit the technical solutions described in the present invention. A person skilled in the art may make various changes or modifications, and all equivalent changes or modifications shall be included in the protection scope of the present invention. Anything not described in detail in the present invention is a known technology to a person skilled in the art.

Claims

1. A cleaning rack capable of rotating a silicon wafer, characterized in that: The invention comprises a frame, a driving motor (2), and a silicon wafer basket (7); the frame comprises a longitudinally arranged top frame (9), a vertically arranged connecting pipe (10) provided with an inner hole (15), and a longitudinally arranged silicon wafer basket frame (1); the bottom end of the connecting pipe (10) is connected to the rear end of the silicon wafer basket frame (1), the top end of the connecting pipe (10) is connected to the top frame (9), and the driving motor (2) is arranged on the top frame (9) directly above the connecting pipe (10); a bottom plate (11) is provided at the bottom end of the connecting pipe (10); and the cross section of the inner hole (15) of the connecting pipe (10) is rectangular; Two parallel rotating rods (4) are longitudinally arranged on the silicon wafer flower basket frame (1); rotating rod mounting holes are longitudinally arranged at the left and right ends of the front side surface at the bottom end of the connecting tube (10); the two rotating rods (4) are respectively inserted into one rotating rod mounting hole; a sprocket (12) is arranged in the inner hole (15) of the connecting tube (10) of each rotating rod (4); the two sprockets (12) are connected via a second transmission chain (5); the plane where the second transmission chain (5) is located is perpendicular to the two rotating rods (4); A driving wheel (13) is provided at the rear end of the driving motor (2); a driven wheel (14) is provided in the inner hole (15) of the connecting pipe (10) of one of the two rotating rods (4); a driving wheel (13) is provided on the driving motor (2), and the planes on which the driving wheel (13) and the driven wheel (14) are located are perpendicular to the two rotating rods (4); The driving wheel (13) and the driven wheel are connected via a first transmission chain (6); the lower end of the first transmission chain (6) is located in the inner hole (15) of the connecting pipe (10); A first sealing sleeve (16) is provided between each rotating rod (4) and the inner hole (15) of the connecting tube (10); A partition (17) perpendicular to the two rotating rods (4) is provided just above the front side of the connecting tube (10) of the top frame (9); a first cavity (18) is provided on the rear side of the upper partition (17) of the top frame (9); and a second cavity (19) is provided on the front side of the upper partition (17) of the top frame (9); the top end of the connecting tube (10) is in communication with the bottom surface of the first cavity (18); A motor shaft mounting hole perpendicular to the partition (17) is provided on the partition (17); the drive motor (2) is mounted in the second cavity (19); a drive shaft (20) is longitudinally provided on the drive motor (2); the drive shaft (20) of the drive motor (2) passes through the motor shaft mounting hole; the driving wheel (13) is mounted on the drive shaft (20) and is located in the first cavity (18); the upper end of the first transmission chain (6) is located in the first cavity (18); a second sealing sleeve (21) is provided between the motor shaft mounting hole and the drive shaft (20) of the drive motor (2); A silicon wafer basket (7) is mounted on the silicon wafer basket frame (1), and a plurality of silicon wafer slots (22) are provided on the silicon wafer basket (7) perpendicular to the two silicon wafer rotating rods (4). When a plurality of circular silicon wafers (8) are placed on the silicon wafer slots (22) in the silicon wafer basket (7), the bottom end of each silicon wafer (8) contacts the radial outer peripheral surface of the two rotating rods (4); The long side of the cross section of the inner hole (15) of the connecting pipe (10) is arranged transversely; A rubber sleeve (26) is provided on the radial outer peripheral surface of the portion outside the connecting tube (10) of each rotating roller (4).

2. The cleaning rack capable of rotating silicon wafers as claimed in claim 1, characterized in that: The silicon wafer flower basket (7) comprises a left frame plate (23) and a right frame plate (24); the front end of the left frame plate (23) and the front end of the right frame plate (24), and the rear end of the left frame plate (23) and the rear end of the right frame plate (24) are connected via a connecting plate (25); a plurality of silicon wafer slots (22) are respectively provided on the left frame plate (23) and the right frame plate (24); the bottom surfaces of the left frame plate (23) and the right frame plate (24) are flush and located below the bottom surface of the connecting plate (25).

3. The cleaning rack capable of rotating silicon wafers as claimed in claim 1, characterized in that: A glass door (27) is provided at the top end of the second cavity (19).

4. The cleaning rack capable of rotating silicon wafers as claimed in claim 1, characterized in that: A plurality of ventilation holes (3) are provided on the front side of the first cavity (18) on the top frame (9).

5. The cleaning rack capable of rotating silicon wafers as claimed in claim 1, characterized in that: The silicon wafer flower basket frame (1) is provided with a silicon wafer flower basket slot (32) with an opening facing upward, and the silicon wafer flower basket (7) is inserted into the silicon wafer flower basket slot (32).

6. Silicon wafer cleaning device, characterized in that: The invention comprises a cleaning device frame (30), a lifting device (29), a cleaning rack capable of rotating silicon wafers as described in any one of claims 1 to 5, and a cleaning tank (28), wherein the rear end of the top frame (9) of the cleaning rack capable of rotating silicon wafers is mounted on the lifting device (29), the lifting device (29) is mounted on the cleaning device frame (30), and the cleaning tank (28) is mounted directly below the silicon wafer basket frame (1) of the cleaning device frame (30).

7. The silicon wafer cleaning device according to claim 6, characterized in that: The lifting device (29) is an electric linear drive.

8. A silicon wafer cleaning device, characterized in that: It comprises a rotatable annular conveying device (31) whose top surface is a horizontal surface, the rotatable annular conveying device (31) is connected to a plurality of lifting devices (29), the bottom end of the lifting devices (29) is connected to a cleaning rack capable of rotating silicon wafers as described in any one of claims 1 to 5, and a cleaning tank (28) is provided below each of the cleaning racks capable of rotating silicon wafers.

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