Abstract:
A clean, recirculating and processing method which prevents surface contamination of an object, such as a semiconductor, semi-conductor wafer, glass for LCD or magnetic disk is provided which includes covering the front and rear surfaces of an object to be processed with front and rear shielding plates and allows the object to rotate relative to the front and rear shielding plates. The fluid is supplied between the front surface of the object and the front shielding plate allowing the front surface to be processed. The remaining fluid is collected and recirculated between the rear surface of the object and the rear shielding plate allowing the rear surface of the object to be processed. An apparatus for accomplishing the method is also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention in related to a fluid processing method of an object to be processed and an apparatus thereof required for the manufacturing process of thin film devices. In particular, the present invention is related to a fluid processing method of an object to be processed and an apparatus thereof suitable for a semiconductor manufacturing process that demands an extremely clean environment. 
     2. Description of the Related Art 
     In recent years miniaturization of the structure of thin film devices such as semiconductors, liquid crystal displays and magnetic disks has been progressing and because of the performance of these devices and improved manufacturing yield rates, this is followed by expectations of extremely clean manufacturing processes. Looking at a semiconductor wafer as an example, the size of the foreign matter to be removed for a wafer of 0.2 um or more should be 10 parts or less per wafer, the amount of contaminants of metal ions should be 10 10  atoms/cm 2  or less, and the thickness of the oxide film formed by contact with air should be 1 nm or less. 
     Furthermore, the mixed production of multiple types of products become unavoidable making necessary equipment that can work with numerous manufacturing processes while putting sheet processing methods which process a plate-shaped object to be processed (hereinafter referred to as simply object to be processed) one wafer at a time. 
     As a first conventional example, FIG. 7 shows a substrate process of Japanese Patent Laid-open No. 08-316190. In this conventional example, a plate-shaped object to be processed  53  is fixed to a substrate retention member  54  and also rotates (rotation means not shown in the figure). In order to prevent the front surface of the object to be processed from becoming contaminated due to the turbulent flow produced by the rotation of the plate-shaped object to be processed  53 , the front surface of the plate-shaped object to be processed  53  is covered by a shielding plate  52  (hereinafter referred to front shielding plate) and a fluid process is carried out in which process fluid is injected onto the front surface of the plate-shaped object to be processed  53  only by means of a pure water injection nozzle  51 . In this first conventional example, because a shielding plate (hereinafter referred to rear shielding plate) is not provided on the rear surface of the plate-shaped object to be processed  53 , the following problems occurred. 
     In addition to the fact that there was no fluid processing of the rear surface, the rear surface of the object to be processed became contaminated due to the turbulent flow generated by the rear surface of the plate-shaped object to be processed  53 . When the rear surface of the object to be processed becomes contaminated, in processes after that the front surfaces of apparatuses such as a transfer arm for the object to be processed that makes contact with the rear surface of the object to be processed and a retention member for the object to be processed (not shown in the figure) undergo transfer contamination and the rear surface of the object to be processed after that becomes even more contaminated reducing the quality of the product. In particular, in processes which are subjected to heat, contaminants developed which were adhering to the rear surface of the object to be processed, reaching the front surface of the object to be processed which in turn caused fatal contamination on the front surface of the object to be processed. 
     As a second conventional example that can solve this problem, FIG. 8 shows a processing method of work and apparatus of Japanese Patent Laid-open No.08-78368. In this conventional example, the rear surface of the object to be processed is also covered by a rear shielding plate  62  to prevent the rear surface of the object to be processed from becoming contaminated due to the above-mentioned turbulent flow along with the front and rear surfaces of the object to be processed undergoing fluid processing simultaneously. 
     However, the object to be processed  64  in this example must be rotated in order to carry out uniform fluid processing on the front surface of the object to be processed. Considering this point, a retention means of the object to be processed  64  is mechanically provided integrally on the rear shielding plate  62  in this second conventional example and the object to be processed  64  and the rear shielding plate  62  are rotated simultaneously with a motor  65 . The fluid is supplied from a supply tank  74  and is then switched by three-way valves  67 ,  68  and diverted to front shielding plate  61  and rear shielding plate  62 . Although the connection structure of a supply pipe  76  to the rear shielding plate  62  is not mentioned in the second conventional example, the one rear shielding plate  62  rotates and the other supply pipe  76  is normally fixed. Further, the symbol  70  is a fresh fluid supply portion. 
     SUMMARY OF THE INVENTION 
     The following problems were present in the second conventional example however. 
     At first, because the fluid that processed the rear surface was contaminated, it cannot be re-utilized even it it is collected in a fixed hood  63 . Because of this, fluid that was switched in a three-way valve  69  and collected in the fixed hood  63  had to be discarded. However, if discarded. large quantities of fluid are consumed. Further, looking at the system drawing of FIG. 8, although it can be seen that the fluid that processed the rear surface utilizes circulation, because the fluid that processed the rear surface has large contamination, circulation cannot be used even if the fluid is filtered by filters  72 ,  75 . 
     Next, if the fixed supply pipe  76  that supplies fluid is connected to the supply opening provided on the rotating rear shielding plate  62  such that fluid does not leak, the connection portion will rub. Rubbing particles mix with the fluid contaminating the fluid and then pass through the fixed hood  63 , a collection tank  71 , a pump  73  and a supply tank  74  reaching to the front shielding plate  61  and then from the start the rear surface of the object to be processed contaminates the front surface of the object to be processed fatally reducing the quality. 
     If the fixed supply pipe  76  that supplies fluid and the rotating rear shielding plate  62  are connected such that they do not rub against one another, fluid will leak from the connection portion and in many oases corrosive material contained within the fluid will corrode parts such as the motor  65 . 
     Thus, a method and an apparatus were not realized which carry out very clean fluid processing on the object to be processed in a sheet process that requires rotation of the object to be processed to allow uniform processing. 
     The topics of the present invention provide solutions to the above-mentioned problem points of the conventional examples. The first topic provides a fluid processing method of an object to be processed that uses circulation of fluid to allow very clean fluid processing at low-cost. The second topic provides a fluid processing apparatus of an object to be processed that allows very clean fluid processing of the front surface of the object to be processed and the rear surface of the object to be processed. The third topic provides a fluid processing apparatus of an object to be processed that can obtain a very clean object to be processed without generating rubbing particles and without fluid leaks. 
     The first method of the invention is a fluid processing method of an object to be processed having a front surface and a rear surface that comprises covering said front surface of said object with a front shielding plate and covering said rear surface of said object with a rear shielding plate wherein contamination of said front and rear surface is prevented and wherein, said object is allowed to rotate relative to said front and said rear shielding plates; supplying a fluid between said front surface of said object and said front shielding plate wherein said front surface is processed; collecting said fluid after said processing of said front surface; and supplying said collected fluid between said rear surface of said object and rear shielding plate wherein said surface is processed. 
     The object to be processed is a plate-shaped substrate such an a semiconductor wafer, glass for a liquid crystal display or a magnetic disk. The retention member for the object to be processed must be a material that can retain the object to be processed against centrifugal force generated by rotation. 
     In the first Invention, fluid used in the processing of the front surface of the object to be processed is collected, this fluid is circulated and supplied to the rear surface of the object to be processed and processing of the rear surface of the object to be processed is carried out. It is not possible to collect fluid used in the processing of the front surface of the object to be processed and carry out processing of the front surface of the object to be processed again although, when the rear surface of the object to be processed has larger contamination compared to the front surface of the object to be processed, there are no hindrances even if fluid processing is carried out using fluid used in the processing of the front surface of the object to be processed. Because the processing of the front surface of the object to be processed is carried out by allowing fluid used in the processing of the front surface of the object to be processed to circulate, the amount of fluid used can be reduced making it possible to achieve low-cost fluid processing. 
     In particular, only the retention member for the object to be processed rotates excluding the hood and if the front shielding plate and the rear shielding plate are arranged so they do not rotate, the supply opening and the fluid supply system provided on the front shielding plate and the supply opening and the circulation system provided on the rear shielding plate do not generate rubbing particles making it possible to easily connect the supply opening and the circulation system provided on the rear shielding plate without a fluid leaks. Therefore, even cleaner low-cost fluid processing can be achieved. 
     In the first invention, it is preferable that said fluid used to process said rear surface is collected and supplied between said rear surface of said object and said rear shielding plate, wherein said rear surface is processed. Because the processing of the rear surface of the object is carried out by circulating fluid having been used the rear surface of the object, the amount of fluid used can be more reduced and more low-cost fluid processing can be achieved. 
     Furthermore, in the first invention, a hood used to capture discharged fluid used in the fluid processing is arranged on the periphery of the object to be processed and designed to rotate on the same axis as the retention member for the object to be processed or the front shielding plate and the rear shielding plate. The rotation of this hood applies a centrifugal force to the discharged fluid from the completed fluid processing used in the fluid processing as well to the retention member for the object to be processed or the front shielding plate and the rear shielding plate and because of this only fluid that completed fluid processing discharged outward radially is captured and collected by the hood. Because the hood rotates along with the retention member for the object to be processed or the front shielding plate and the rear shielding plate, the centrifugal force acts on the discharged fluid that completed fluid processing which in turn controls the flow in the direction of the rotating axle of the retention member for the object to be processed or the front shielding plate and the rear shielding plate. Therefore, the discharged fluid that completed fluid processing is effectively collected in the collection portion without leaking from the direction of the rotating axle. Thus, because the hood is allowed to rotate and a centrifugal force is applied to discharged fluid as well as to the retention member for the object to be processed or the front shielding plate and the rear shielding plate controlling the flow in the direction of the rotating axle, the fluid can be effectively collected making it possible to achieve low-cost fluid processing. 
     Moreover, in the first invention, fluid that completed fluid processing of the front surface of the object to be processed can be mixed with fluid that completed fluid processing of the rear surface of the object to be processed and then collected. This collected fluid can be circulated and supplied to the rear surface of the object to be processed and then processing of the rear surface of the object to be processed carried out. According to this operation, because contamination of the fluid used in the processing of the rear surface of the object to be processed is diluted by means of mixing and collecting fluid that completed fluid processing of the rear surface of the object to be processed with fluid that completed fluid processing of the front surface of the object to be processed, processing of the rear surface of the object to be processed can be carried out by circulating the collected fluid to the rear surface of the object to be processed making it possible to achieve even more economical fluid processing. 
     Even further, fluid to be supplied in proportion to the processing that should be carried out for the object to be processed can be selected and processing of the front and rear surfaces of the object to be processed can be carried out. If a washing process is given as an example for the process that should be carried out for the object to be processed, three processes of washing, rinsing and drying can be done in one step. For this case, the washing fluid would consist of a fixed proportion of, for example, ammonia+hydrogen peroxide+water or hydrofluoric acid+water, the rinse would consist of super pure water and the drying would use an inert gas such as argon or N 2  gas. According to this operation, because fluid to be supplied to the processing is selected and processing of the front and rear surfaces of the object to be processed is carried out, combining of processes can be designed improving the efficiency of the fluid processing even more. 
     The second invention is a fluid processing apparatus of an object to be processed that comprises a retention member for the object to be processed that retains the object to be processed, front and rear shielding plates which shield both the front surface and the rear surface of the object to be processed retained by the retention member for the object to be processed and rotate relative to the retention member for the object to be processed, a fluid supply system that supplies fluid between the front shielding plate and the front surface of the object to be processed through a supply opening provided on the front shielding plate, a hood that captures liquid that at least completed fluid processing of the front surface of the object to be processed, a collection portion that collects said fluid that completed fluid processing captured by the hood from an outlet opening provided on the hood, and a circulation system that supplies the fluid that completed fluid processing collected means of the collection portion between the rear shielding plate and the rear surface of the object to be processed through a supply opening provided on the rear shielding plate in order to carry out fluid processing in the rear surface of the object to be processed and then collects the fluid that completed fluid processing of said surface of the object to be processed. 
     When fluid is supplied from the circulation system to the supply opening provided on the rear shielding plate, processing of the rear surface of the object to be processed is carried out. The liquid that completed processing of the front and rear surfaces of the object to be processed is captured by the hood and collected and mixed in the collection portion. At this time, because the fluid that becomes greatly contaminated due to the processing of the rear surface of the object to be processed is diluted by means of fluid wherein the contamination is halted at a comparatively small level due to the processing of the front surface of the object to be processed, the level of contamination is reduced. Therefore, by means of circulating this fluid mixture with a reduced level of contamination to the rear surface of the object to be processed, there are no hindrances to the fluid processing even if processing of the rear surface of the object to be processed is carried out. 
     In the second invention, it is preferable that said hood is arranged to rotate on the same axis as said retention member for the object to be processed or said front shielding plate and said rear shielding plate, and a centrifugal force generated by said rotation is received capturing the fluid that completed fluid processing of the front surface of the object to be processed and the fluid that completed fluid processing of the front surface of the object to be processed both discharged from the periphery of said object to be processed. 
     Further, when the front shielding plate and the rear shielding plate are fixed to the retention member for the object to be processed, the connections of a fixed type fluid supply pipe for the supply openings can utilize a fixed type method without generating rubbing particles and without leakage of fluid. Because fluid is supplied from the fixed type fluid supply pipe to the supply openings provided on both the fixed front shielding plate and rear shielding plate, the retention member of the object to be processed is mechanically provided integrally allowing a connection at the connection portion between the supply openings and the fluid supply pipes without generating rubbing particles and without generating rubbing particles and without leakage of fluid compared to a case when supplying fluid to supply openings provided on a rotating rear shielding plate. Therefore, very clean fluid processing with the addition of rubbing particles can be achieved. Corrosion of parts such as the rotation drive source due to corrosive materials contained within the fluid occurring because of fluid leaks can be prevented as well. 
     For a case when the retention member of the object to be processed is fixed and the front shielding plate and rear shielding plate are allowed to rotate, friction occurring in the connection portion is eliminated an much as possible using a bearing with a small amount of friction. 
     In the second invention, when the retention member of the object to be processed is allowed to rotate, this retention member can be comprised by a hollow rotating axle provided on the rear shielding plate wherein a supply opening is provided, a retention portion provided on the periphery of the object to be processed that retains the periphery of the object to be processed, and a linkage portion that protrudes from the rotating axle outward radially reaching close to the periphery of the rear shielding plate and that links the retention portion to the rotating axle. Further, the hood can be comprised by an external hood that covers the travel path of the fluid discharged from the periphery of the object to be processed and an internal hood that covers the lower portion of the travel path and in addition at least the internal hood rotates on the same axis as the retention member for the object to be processed. 
     Even further, the rotating retention member for the object to be processed and the hood can be comprised integrally or the retention member for the object to be processed and the hood can be formed separate and separate rotation control can be provided for either of them. A mechanism can also be provided that regulates the circulation flowrate of fluid in the circulation system and for this case, the mechanism that regulates the circulation flovrate can be a cyclone separator that utilizes the centrifugal force of fluid. 
     Moreover, it is preferable for the front shielding plate and rear shielding plate to be formed by carbon or fluoride resin. It is also preferable for the collection portion to be fixed and the outlet opening of the hood being inserted into this fixed collection portion without making contact. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a compositional drawing of the fluid processing apparatus according to an embodiment of the present invention; 
     FIG. 2 is an enlarged perspective view of the principal components of the retention member for the object to be processed; 
     FIG. 3 is a compositional drawing of a modified example of an embodiment of the present invention; 
     FIG. 4 is a compositional drawing of the fluid proosssing apparatus according to another embodiment of the present invention; 
     FIG. 5 is a compositional drawing of the fluid processing apparatus according to another embodiment of the present invention; 
     FIG. 6 is a drawing of a piping system that shows the fluid processing apparatus according to an embodiment of the present invention and the circulation of fluid; 
     FIG. 7 is a compositional drawing showing a first conventional example: 
     FIG. 8 is a compositional drawing showing a second conventional example. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, preferred embodiments of the present invention will be described with reference to the attached drawings. Referring to FIG. 1, a method will be described wherein the front and rear shielding plates are fixed, the object to be processed rotates while being retained and fluid is collected. 
     The front shielding plate  11  and the rear shielding plate  15  are fixed with the intent not to rotate (fixed method not shown in the figure). The front shielding plate  11  is arranged such that it rises when the object to be processed  17  is retained. The front shielding plate  11  and the rear shielding plate  15  are arranged almost parallel without making contact with the surface opposite to the object to be processed  17 . The distance between the object to be processed  17  and the front shielding plate  11  and the rear shielding plate  15  can be determined to meet type of fluid and the objectives of the fluid processing. 
     The front shielding plate  11  has a somewhat large disk shape with a diameter larger than the object to be processed  17 . By means of covering the front surface of the plate-shaped object to be processed  17 , contamination on the front surface of the object to be processed caused by turbulent flow due to the rotation of the plate-shaped object to be processed  17  is prevented. A front supply opening  19  is opened at the center of the front shielding plate  11 , fluid is supplied from this front supply opening  19  between the front surface of the object to be processed and the front shielding plate  11  opposite to this to carry out processing of the front surface of the object to be processed. As can be seen in the cross-sectional view, a tapered surface  21  is formed on the periphery of the front shielding plate  11  from the side of the rear surface facing toward the outside of the front surface. A thin collar-shaped external hood receiver  42  is formed thinner than the entire thickness of the front shielding plate  11  at the end of the tapered surface  21 . 
     The rear shielding plate  15  has a somewhat small disk shape with a diameter smaller than the object to be processed  17 . By means of covering the rear surface of the plate-shaped object to be processed  17 , contamination on the rear surface of the object to be processed caused by turbulent flow due to the rotation of the plate-shaped object to be processed  17  is prevented. A rear supply opening  20  longer than the front supply opening  19  is opened at the center of the rear shielding plate  15 , fluid is supplied from this rear supply opening  20  between the rear surface of the object to be processed and the rear shielding plate  15  opposite to this to carry out processing of the rear surface of the object to be processed. 
     A retention member for the object to be processed  18  is arranged at a position with almost an identical diameter as the object to be processed  17  on the periphery of the rear shielding plate  15  such that the object to be processed  17  is mechanically retained. The retention method using the retention member for the object to be processed  18  of the object to be processed  17  is not related to the present invention and can be a separate mechanical method that takes into consideration the mounting and removal of the object to be processed and the shape and strength of the object to be processed. For example, as shown in FIG. 2, it is sufficient to provide a retention member for the object to be processed  24  at four locations on the outer circumference of the front surface of a disk portion  23  as a linkage portion and retain the edge of the outer circumference of the object to be processed  17  using this retention member for the object to be processed  24 . 
     Other than the retention member for the object to be processed  24 , the retention member for the object to be processed  18  is comprised by disk portion  23  that has hole  26  in the center piercing the retention member for the object to be processed  24  on the periphery, a tubular rotating axle  25  that passes through the hole and links the center of the rear surface of the disk portion  23 , and a motor  14  connected to the rotating axle  25 . The retention member for the object to be processed  18  is also disposed to freely rotate by means of the motor  14 . A disk-shaped portion  41  of the rear shielding plate  15  is arranged on the disk portion  23  of the retention member for the object to be processed  18  vithout making contact. The rear supply opening  20  of the rear shielding plate  15  in extracted from the inside of the tubular rotating axle  25  of the retention member for the object to be processed  18  without making contact. Therefore, the retention member for the object to be processed  18  is arranged so it does not make contact with the rear shielding plate  15  (does not rotate) so only the object to be processed  17  rotates by means of the motor  14 . 
     Even further, as shown in FIG. 3, for example, the retention member for the object to be processed  18  can have a composition in which the internal hood  16  is connected mechanically. The rotating axle  25  need not consist of one member but can be comprised to have a rotating axle  40 . The rotating axle  25  and the internal hood  16  rotate FFF1DEG (approximately 90 DEG) although the rotating axle  40  does not rotate until the rotating axle  25  and the internal hood  16  rotate FF1DEG and when FFF1DEG or more is reached, the rotating axle  25 , the internal hood  16  and the rotating axle  40  can all be made to rotate. Therefore, while the rotating axle  25  and the internal hood  16  rotate until FFF1DEG, the retention member for the object to be processed  18  rotates FFF2DEG and is twisted. The magnitude of FFF2DEG can be determined by the gear ratio of the internal hood  16 , the rotating axle  40  and the retention member for the object to be processed  18 . Accordingly, it is possible to mount and remove the retention member for the object to be processed  18  of the plate-shaped object to be processed  17  utilizing the twisting of the retention member for the object to be processed  18 . 
     A hollow approximate ring-shaped hood  27  is disposed on the periphery of the retention member for the object to be processed  18 . This hood is integrally mounted to the retention member for the object to be processed  18  and rotates together with the member  18 . Fluid that completed processing and was discharged outward radially from between the front shielding plate  11  and the rear shielding plate  15  by the centrifugal force generated by the rotation of the retention member for the object to be processed  18  is admitted from an upper portion inlet  28  of the hood  27  that borders the gap between the front shielding plate  11  and the rear shielding plate  15  and then gently turns and guides the fluid in that direction downward with the fluid then being discharged from a lower portion outlet  29  of the hood  27 . 
     This hood  27  is constructed by radially shifting the gap between the external hood  12  and the internal hood  16 . The upper portion of the external hood  12  in the cross section is gently bent radially inward from the lower portion in a straight line, is inserted into the lower side of the collar-shaped external hood receiver  42  of the front shielding plate  11  and is then pressed until reaching the front of the tapered surface  21 . Therefore, the diameter of the upper edge of the external hood  12  is smaller than the external diameter of the front shielding plate  11  but is larger than the mounting diameter of the retention member  24  of the retention member for the object to be processed  18 . The reason the diameter of the upper edge of the external hood  12  is made smaller than the external diameter of the front shielding plate  11  is because fluid that completed processing is effectively captured within the hood  27  and if it is made larger than the external diameter of the front shielding plate  11 , there is the possibility that fluid may leak from the gap between the front shielding plate  11 . Further, the reason the diameter of the upper edge of the external hood  12  is made larger than the mounting diameter of the retention member  24  is to prevent it from invading into the processing region of the object to be processed and if it is made smaller than the mounting diameter of the retention member  24 . there is a possibility that fluid before the processing will flow into the hood  27  and cause problems with the processing of the end portion of the object to be processed  17 . 
     Fluid is introduced into the hood  27  is by centrifugal force even if the fluid drops due to the internal hood  16  arranged in a shape similar to the inside of external hood  12 . 
     The lower portion outlet  29  of the hood  27  formed on both lower edges of the external hood  12  and the internal hood  16  is inserted into a tubular collection tube  13  without making contact making it possible to collect fluid that completed processing and was captured by the hood  27  falling into the hood  27  by gravity or by suction. 
     Fluid supplied from the supply openings  19 ,  20  positioned at the center portion of the front and rear shielding plates  11 ,  15  is discharged from the periphery of the object to be processed  17  while processing the front surface and the rear surface of the object to be processed  17 . The discharged fluid is deflected downward from the external hood  12  or is held on the front surface of the internal hood  16  by means of gravity of suction. Because the internal hood  16  rotates together with the retention member for the object to be processed  18 , centrifugal force acts on the discharged fluid controlling the flow towards the retention member for the object to be processed  18  or the direction of the rotating axle  25  of the internal hood  16 . Because of this, the discharged fluid is reliably collected in the collection tube  13  without returning during the collection. 
     Further, the approximate ring-shaped hood  27  can be separated from the retention member for the object to be processed  18  and not rotate. 
     The collection tube  13  is fixed with the intent not to rotate and as described above, does not make contact with the rotating internal hood  16 . Moreover, the external hood  12  can be fixed with the intent not to rotate although. preferably, can be connected to the internal hood  16  and allows to rotate in order to increase the collection efficiency. The external hood  12  is also retained on the collection tube  13  without making contact. Further, because the rear shielding plate  15  does not rotate, the connection portion  30  between the supply opening  20  provided on the rear shielding plate  15  and the fluid supply pipe  22  (fixed system) can be rigid. Therefore, rubbing particles are not generated in the connection portion  30  and there are no fluid leaks. Even further, if rubbing particles are not generated and there are no fluid leaks, a connection can be established using a means other than a rigid connection. Fluid discharged from between the front and rear shielding plates  11 ,  15  by means of the action of the centrifugal force of the external hood  12  and the internal hood  16  does not leak making it possible to reliably collect the fluid in the collection tube  13 . 
     Next, another embodiment shown in FIG. 4 of an very clean fluid processing method identical to FIG. 1 will be described. This embodiment is identical to the embodiment in FIG. 1 except for the retention member for the object to be processed  38  and the internal hood  36  (which were integral in FIG. 1) being separated as well as making possible independent rotation control. The retention member for the object to be processed  38  and the internal hood  36  are comprised to be separate members and have rotating axles  39 ,  37  on the axis and motors  32 ,  31  linked to each rotating axle to provide independent rotation. 
     From the start, the objective of allowing the retention member for the object to be processed  38  to rotate and the objective of allowing the internal hood  36  to rotate were different. This is because the former carries out uniform fluid processing on the front surface of the object to be processed and the latter allows centrifugal force to act on the fluid discharged from between the front and rear shielding plates  11 ,  15  controlling the flow towards the retention member for the object to be processed  38  or the direction of the rotating axles  39 ,  37  of the internal hood  36 . Therefore, the rotational force of the internal hood  36  is sufficiently smaller than that of the retention meiber for the object to be processed  38 . If the rotational force is large and a powerful centrifugal force is applied, the strength of the apparatus must be increased. Considering this point, because the rotational force of the internal hood  36  can be dropped less than that of the retention member for the object to be processed  38 , it is also possible to use a low-cost plastic for the material of the internal hood  36  that is formed integrally wlth the internal hood  36 . Further, in contrast, it is also possible to increase the rotational force of the retention member for the object to be processed  18  and further use the centrifugal force to increase the performance. Because either can be used to select a rotation that meets the needs of the user, rotation of the internal hood  36  can be stopped to improve the operating conditions of the user. Moreover, the two rotating axles  37 ,  39  can be rotated by gear transmission using one motor. 
     Descriptions were provided above for the embodiments of FIG. 1 to FIG. 4 in which the retention member for the object to be processed  18  or the object to be processed  17  rotate and the front shielding plate  11  and the rear shielding plate  15  are fixed. However, the present invention can be applied for a case when the object to be processed  17  and the front and rear shielding plates  11 ,  15  rotate relative to each other. As an example of this relative rotation, when the object to be processed and the front and rear shielding plates rotate relative to each other for embodiments other than the above-mentioned, the retention member for the object to be processed can be fixed and the front and rear shielding plates can rotate. Hereupon, the latter case will be described referring to FIG. 5 in which the retention member for the object to be processed  83  is fixed and the front and rear shielding plates  81 ,  82  rotate. 
     The apparatus shown in FIG. 5 is comprised such that the front and rear shielding plates  81 ,  82  are not fixed but rotate and is fundamentally identical to the embodiment in FIG. 4 except for the fact that the retention member for the object to be processed  83  does not rotate but is fixed. In other words, the motor is removed from the retention member for the object to be processed  83  and then the retention member for the object to be processed  83  is fixed. Motors  84 ,  85  are mounted on the front and rear shielding plates  81 ,  82 , respectively so the front and rear shielding plates  81 ,  82  freely rotate on the smeo axis. Since the front and rear shielding plates  81 ,  82  are allowed to rotate here, each connection portion between the supply openings  19 ,  20  provided on the front and rear shielding plates  81 ,  82  and the supply pipes  89 ,  90  (fixed system) becomes a problem. As described above, if a connection is made such that not fluid leaks in the supply openings  19 ,  20 , the connection portions will rub. If a connection made such that there is no rubbing, fluid will leak from the connection portion. However, by means of using low friction bearings  86 ,  87  in the connection portion, the occurrence of rubbing is reduced making possible to effectively prevent rubbing particles from mixing in with the fluid. For the low friction bearings  86 ,  87  the following types of bearings can be used. 
     A magnetized fluid bearing that uses magnetized fluid. 
     A fluid membrane bearing that uses a fluid membrane. 
     A magnetic bearing wherein the supply pipes  89 ,  90  are made to rise using magnetism along with the gap between them being filled with a magnetized fluid or fluid membrane. 
     A dynamic pressure bearing that supports a moving body using dynamic pressure force of fluid. 
     A static force bearing that supports a moving body using static force of fluid. 
     A high-precision static force air bearing within a static force bearing. 
     A composite magnetic bearing (comprising a combination of a suction type or repulsive type permanent magnet and at least one group of active type [controls electromagnet currents] magnetic bearings. 
     Compared to the apparatus of FIG. 4, although the number of motors is increased, the front and rear shielding plates  81 ,  82  which hold the object to be processed  17  between them rotate on both sides of the object to be processed  17 . Because of this, a strong centrifugal force acts on the fluid to be supplied thereby improving the uniformity of the fluid processing of the front surface of the object to be processed and in addition has a large effect on the discharge of fluid that completed processing. 
     Next, referring to FIG. 6, a low-cost fluid processing method of the present invention and a very clean and low-cost fluid processing apparatus wvil be described. 
     The principal components of the fluid processing apparatus are those used in FIG. 1. A fluid processing fluid container  116  can supply fluid processing fluid to a front supply pipe  122  through a pump  109  and a valve  108 . In addition, to the fluid processing fluid, an inert gas can be supplied to the front supply pipe  122  through a valve  102  and a fluid processing fluid, such as super pure water, can be supplied to the supply pipe  122  through a valve  106 . 
     A collection tube  103  is connected to a separator  112  through a pipe  121  and the separator  112  is connected to a rear supply pipe  104  through a valve  110  from a pump  114  passing through a heater  115  and then through a filter  113  and a circulation system  120  for fluid collected in these is provided. Further, the front supply pipe  122  is linked to the rear supply pipe  104  through a valve  111 . 
     Now, a fluid processing method for the object to be processed that uses a fluid processing apparatus that has the above-mentioned system wil be described. 
     Initially, the valves  108 ,  110  open, the valve  111  closes, fluid processing fluid Is drawn up from the fluid processing fluid container  116  by the pump  109  and then the fluid processing fluid is supplied to the object to be processed  107  from a front shielding plate  101 . While the fluid processing fluid processes the front surface of the object to be processed  107 , the fluid discharges from the end of the object to be processed  107 , is captured by a hood  119  and to collected in the collection tube  103 . The separator  112  constantly carries out suction discharge and the fluid processing fluid of the collection tube  103  is sucked from between external and internal hoods  117 ,  118  and the collection tube  103  entering into the outside air and Is then introduced into the separator  112 . The fluid processing fluid accumulates at the bottom of the separator  112  by current flow and gravity that occurs naturally Inside the separator  112 . When the fluid processing fluid fills up the separator  112 , it is automatically discharged into the outside air. The fluid processing fluid accumulated at the bottom of the separator  112  passes through the pump  114 , the heater  115  and the filter  113  and is supplied to a rear shielding plate  105  through the rear supply pipe  104 . And during fluid processing of the rear surface of the object to be processed  107 , the fluid is collected in collection tube  103 . 
     For most of the object to be processed  107 , the rear surface from the front surface is noticeably contaminated due to transport and retention of the object to be processed. Therefore, the fluid used to process the rear surface cannot process the front surface. However, there is no impediment in using the fluid used to process the front surface to process the rear surface. Further, the fluid used to process the rear surface is constantly mixed In the collection tube  103  by means of the fluid used to process the front surface. Therefore, the collected fluid is retained in an almost fresh state and even if it to allowed to circulate, contaminants will not accumulate in the fluid supplied to the rear shielding plate  105 . 
     When the separator  112  Incorporated in the circulation system  120  circulates fluid to the rear shielding plate  105 , excessive fluid is automatically discharged. Because of this, the circulation flowrate of fluid, circulated by the circulation system  120  is automatically regulated. If these is no need to automatically discharge excessive fluid, this separator  112  is not required and simply separating gas and fluid is sufficient using a gas/fluid separator that uses, for example, a reverse osmosis method or a hollow system method. Moreover, if there is no need to precisely control the temperature of the fluid processing fluid, the heater  115  is not particularly needed. If the size of the contamination of the object to be processed  107  in small, the filter  113  is not particularly needed either. The point is that a fluid circulation function to process the rear surface need not be exhibited by adding fluid used to process the front surface of the object to be processed  107  to fluid that processed the rear surface of the object to be processed  107  and was collected. 
     Therefore, the valve  110  closes, the valves  108 ,  111  open, fluid from the fluid processing fluid container  116  is supplied to both the front shielding plate  101  and the rear shielding plate  105 , this fluid is collected and then discharged from the separator  112 . Compared to a conventional apparatus, it is possible to make do with a fluid consumption quantity of half or less and furthermore, a very clean and low-cost fluid processing method can be achieved without rubbing particles mixing in with the fluid. Moreover, in FIG. 6, if the fluid discharged from the separator  112  (although not shown in the figure) is not interfered with, it can be returned to the fluid processing fluid container  116  and used again. 
     The present invention was described as an example of being used to clean silicon wafers. However, if the invention is a fluid processing method of a plate-shaped object to be processed, it is not limited to this example. For example, if each of the materials of the composition of the invention are selected such that electrical current is allowed to flow in the front shielding plate, the rear shielding plate and the plate-shaped object to be processed. it can also be used in electrolytic deposition. 
     &lt;WORKING EXAMPLE 1&gt; 
     In this working example the following materials, components, object to be processed, fluid and fluid processing operations were used to carry out an evaluation. 
     (1) Material 
     Front shielding plate  101 , rear shielding plate  105 : A very pure glass type carbon 20 mm thick 
     External hood  117 , internal hood  118 : Very pure silicon carbide 
     Collection tube  103 : Polytetrafluoroethylene (hereinafter referred to as PTFE) 
     (2) Components 
     Separator  112 : PTFE cyclone with a diameter of 5 cm 
     Pumps  109 ,  114 : Ivaki bellows pumps FA-2E 
     Heater  115 : Komatsu Electronics CS heater AIH-33 
     Filter  113 : Nihon Millipore Fully Teflon filter 
     Valves  102 ,  106 ,  108 .  110 ,  111 : Advance Air operated valves SAV-3240 
     Fluid processing fluid container  116 : 20 liter (1) PTFE container 
     (3) Object to be Processed 
     The object to be processed is an 8 inch wafer with a diameter of 200 mm, a thickness of 0.725 mm and a resistivity of 6.01 to 12.0 Ohms cm manufactured by Shin-Etsu Chemical. 
     This wafer was immersed for 15 minutes in a fluorine aqueous solution of 50% fluorine hydroacid:water=1:99 wherein is added silicon particles with diameters of approximately 0.2 m and approximately 6000 silicon particles were attached to the front surface of the wafer. The washing performance was determined from the removal rate of these silicon particles. 
     (4) Fluid 
     The fluid processing fluid was an aqueous solution of 28% ammonia water:30% hydrogen peroxide:water=1:2:7 at a temperature of 80°C. 
     Inert gas: Nitrogen at room temperature 
     (5) Fluid Processing Apparatus 
     The front shielding plate  101  was raised up, the object to be processed  107  was retained and the rear shielding plate  105  was raised. 
     The object to be processed  107  was rotated at 500 rpm. The valves  108 ,  110  were opened, the valves  102 ,  106 ,  111  were closed and the fluid from the fluid processing fluid container  116  was supplied to the front shielding plate  101  at a flowrate of 1.5 liters/min by the pump  109 . Next, the fluid used to process the front surface of the object to be processed  107  was separated and collected by the cyclone separator  112  and then circulated and supplied to the rear shielding plate  105  at a flowrate of 1.5 liters/min by the pump  114  through the heater  115  and the filter  113 . 
     After this fluid processing was carried out for three minutes, the pumps  109 .  114  stopped, the valves  108 ,  110  closed, the valves  106 ,  111  opened, super pure water was supplied to the front shielding plate  101  and the rear shielding plate  105  and fluid was rinsed for 30 seconds. Next, the valve  106  closed, the valve  102  opened, nitrogen gas was supplied to both the front shielding plate  101  and the rear shielding plate  105  and the object to be processed  107  was rotated at 1000 rpm. 
     After carrying this out for 90 seconds, the valve  102  was closed, the front shielding plate  101  was raised and the wafer of the object to be processed  107  removed. 
     (6) Removal Rate Evaluation of Silicon Particles 
     The results of measuring the number of adhering particles using a laser surface inspection apparatus manufactured by Hitachi Electronics Engineerlng after the above-mentioned fluid processing were less than 10 particles/wafer and it was understood that a very clean fluid processing was carried out in an extremely short time. 
     &lt;WORKING EXAMPLE 2&gt; 
     Other than that shown below, the materials, components, fluid, fluid processing operations and evaluation were identical to &lt;Working Example 1&gt;. 
     (1) Material 
     Rear shielding plate  105 : 20 mm thick Polytetrafluoroethylene 
     (2) Object to be Processed 
     Used a wafer identical to the &lt;Working Example 1&gt;. 
     This wafer was processed for 10 minutes at 80°C. in an aqueous solution of 28% ammonia water:30% hydrogen peroxide:water=1:2:7. Next, the wafer was imersed for 2 minutes in a fluorine aqueous solution of 50% fluorine hydroacid:water=1:99 and the oxidation film was removed from the front surface of the wafer. After a water wash, for 30 minutes the wafer was immersed in an aqueous solution diluted by a standard solution for atomic absorption spectrometry of nickel and producing a wafer with approximately 10 12  atoms/cm 2  contaminants of metal ions of nickel. 
     (3) Fluid 
     Aqueous solution of 36% hydrochloric acid:20% hydrogen peroxide:water=1:1:5 at a temperature of 80° C. 
     (4) Fluid Processing Operations 
     The order of the operations was identical to the &lt;Working Example 1&gt; although the fluid processing time in this working ezample was 90 seconds. 
     (5) Evaluation of the Removal Rate of Metal Ions 
     It was understood that the number of adhering metal ions after the above-mentioned processing was carried out was measured using a ‘Technos’ Fully Reflecting Fluorescent X-ray analyzer (TREX 610) and 6×10 9  atoms/cm 2  was attained. In addition it was understood that speedy and very clean fluid processing could be carried out. 
     &lt;WORKING EXAMPLE 3&gt; 
     Other than that shown below, the materials, components, fluid, fluid processing operations and evaluation were identical to &lt;Working Example 1&gt;. 
     (1) Components 
     Heater  115 : Komatsu Electronics chemical circulator NE-33C-7 
     (2) Object to be Processed 
     Used a wafer identical to &lt;Working Example 1&gt;. The front surface of this wafer was coated with polysilicon with differences in grade. 
     (3) Fluid 
     Aqueous solution of 50% hydrochloric acid:water=1:99. Temperature was room temperature. 
     (4) Fluid Processing Operations 
     The order of the operations was identical to the &lt;Working Example 1&gt; although the fluid processing time In this working example was 90 seconds. 
     (5) Evaluation of Water Mark 
     A water mark is a drying stain that occurs while drying the wafer. The main reason water marks occur is that oxygen in the air dissolves in water droplets adhering on the wafer, oxidizing the silicon of the wafer which then dissolves leaving the dissolved material on the wafer as dried remaining material. 
     The size of these water marks is a diameter of 1 to 10 m and they were measured using a Hitachi electron microscope S-7100. 
     The results of the measurements found 0 to 2 parts/cm 2  and it was understood that compared to the approximately 8 parts/cm 2  of the batch method which is the fluid processing method currently being widely used, this is a very clean fluid processing method. 
     According to the present invention, a low-cost and very clean fluid process can be achieved by means of collecting and circulating a fluid which was used for fluid processing of the front surface of an object to be processed and then supplying that fluid to the rear surface of the object to be processed. 
     Furthermore, according to the apparatus of the present invention, a very clean fluid process can be achieved without generating rubbing particles from the supply of fluid to front and rear shielding plates by means of securing the front and rear shielding plates and allowing only the object to be processed to rotate. 
     Even further, according to the apparatus of the present invention, a very clean and low-cost fluid process of the above-mentioned method can be achieved by just a simple composition wherein only a retention member for the object to be processed is allowed to rotate relative to the front and rear shielding plates along with providing a circulation system that dilutes fluid which underwent rear surface processing in fluid which underwent front surface processing and that allows that fluid to circulate to the rear surface of the object to be processed.