Patent Publication Number: US-2004053509-A1

Title: Fluid treatment system

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a fluid treatment system that applies fluid treatment to substrates such as semiconductor wafers.  
       BACKGROUND ART  
       [0002] As an apparatus that forms metal layers on the surfaces of substrates such as semiconductor wafers (hereinafter, simply referred to as ‘wafers’), for example, a physical vapor deposition apparatus (a PVD apparatus) that forms metal layers in vapor phase has been conventionally used.  
       [0003] However, with the recent improvement in the degree of integration of semiconductor devices, the use of a plating unit that forms metal layers in liquid phase is becoming on the mainstream in light of the problem of an embedding property.  
       [0004] In general, such a plating unit is often incorporated in a plating system for use. Besides the plating unit, a washing unit that washes a plated surface with a pure water or a chemical solution after the surface to be plated of a wafer is plated, and a drying unit that dries the wafer after the plating on the wafer is washed in this washing unit are disposed in the plating system. Since these processing units are disposed in the plating system, a series of processes involved in plating is continuously performed.  
       [0005] A housing of the plating system as described above is generally formed of metal such as iron. Forming the housing of metal, however, has a problem of causing the corrosion of the housing due to mist of a plating solution which is discharged from the plating unit when the wafer is carried therein/therefrom.  
       [0006] In order to solve this problem of the corrosion of the housing, coating the metal housing with synthetic resin or covering the metal housing with synthetic resin film has been proposed.  
       [0007] Coating the metal housing with the synthetic resin, however, has such a problem that the corrosion of the housing cannot be effectively prevented since the housing cannot be maintained airtight due to a porous property of the coating. It has another problem of causing wafer contamination since a solvent and materials contained in a coating compound evaporate to scatter in a clean room. There is still another problem of causing cost increase since pretreatment such as a blast process is required because the state of a base is important in coating.  
       [0008]FIG. 13 is a vertical sectional view schematically showing a part of a housing covered with a synthetic resin film.  
       [0009] In order to cover a metal housing with a synthetic resin film, a film  101  is made to cover a housing  102  from two directions and end portions thereof are welded together, as shown in FIG. 13.  
       [0010] However, it is difficult to maintain the housing  102  airtight in such welding. To be more specific, there is a problem of the corrosion of the housing  102  since, at the time of this welding, a hole  103  is formed due to insufficient welding and mist of a plating solution enters from this hole  103 . Further, since the housing  102  is simply covered with the film  101 , the housing  102  cannot be maintained airtight, and thus a space  104  is made between the film  101  and the housing  102 . As a result, ions enter the space  104  to cause the problem that the housing  102  is corroded at a portion thereof in contact with the space  104 . Moreover, for example, when two pipes different in diameter are welded together to form a part of the housing, there is a problem of the corrosion of the housing since simple covering with the film causes a space to be made in a welded portion due to the change in diameter in the welded portion.  
       DISCLOSURE OF THE INVENTION  
       [0011] The present invention is made in order to solve the conventional problems stated above, and it is an object of the present invention to provide a fluid treatment system in which a housing can be maintained airtight and the corrosion of the housing can be prevented.  
       [0012] A fluid treatment system according to an aspect of the present invention is characterized in that it includes: a fluid treatment unit configured to apply fluid treatment to a substrate; and a housing which houses the fluid treatment unit, the housing being at least partly covered with a synthetic resin film through heat contraction.  
       [0013] As the substrate, for example, a wafer or an LCD glass substrate for liquid crystal is usable. The fluid treatment unit is not limited to any specific one as long as it is a unit capable of applying treatment to a substrate using a fluid. An example of such a fluid treatment unit is a plating unit. The housing can be formed, for example, of a frame and a panel, or only of a panel.  
       [0014] Since the fluid treatment system according to the aspect of the present invention has the housing which houses the fluid treatment unit, the housing being at least partly covered with the synthetic resin film through heat contraction, it is possible to maintain the housing airtight to prevent the corrosion of the housing.  
       [0015] The housing in the abovementioned fluid treatment system preferably has a panel in a substantially planar shape at least partly covered with a synthetic resin film through heat contraction. Since such a panel is provided, the corrosion of the panel can be prevented at a part thereof covered with the synthetic resin film.  
       [0016] The housing of the abovementioned fluid treatment system preferably has a frame at least partly covered with a synthetic resin film through heat contraction. Since such a frame is provided, the corrosion of the frame can be prevented at a part thereof covered with the synthetic resin film.  
       [0017] A fluid treatment system according to another aspect of the present invention is characterized in that it includes: a fluid treatment unit configured to apply fluid treatment to a substrate; and a housing which houses the fluid treatment unit, the housing being at least partly covered with a synthetic resin film through lamination.  
       [0018] Since the fluid treatment system according to the aspect of the present invention has the housing which houses the fluid treatment unit, the housing being at least partly covered with the synthetic resin film through lamination, it is possible to maintain the housing airtight to prevent the corrosion of the housing.  
       [0019] The housing in the abovementioned fluid treatment system preferably has a panel in a substantially planar shape at least partly covered with a synthetic resin film through lamination. Since such a panel is provided, the corrosion of the panel can be prevented at a part thereof covered with the synthetic resin film.  
       [0020] The housing of the abovementioned fluid treatment system preferably has a frame at least partly covered with a synthetic resin film through lamination. Since such a frame is provided, the corrosion of the frame can be prevented at a part thereof covered with the synthetic resin film.  
       [0021] The synthetic resin film in the abovementioned fluid treatment system is formed of at least any one of polyetheretherketone, polycarbonate, polyethylene, polyethylene terephthalate, and polypropylene. The use of such synthetic resin makes it possible to provide a synthetic resin film excellent in fluid resistance, workability, strength, and so on. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0022]FIG. 1 is a perspective view schematically showing a plating system according to an embodiment, which includes a fragmentary enlarged view.  
     [0023]FIG. 2 is a see-through perspective view schematically showing the plating system according to the embodiment.  
     [0024]FIG. 3 is a plane view schematically showing the plating system according to the embodiment.  
     [0025]FIG. 4 is a see-through plane view schematically showing the plating system according to the embodiment.  
     [0026]FIG. 5 is a front view schematically showing the plating system according to the embodiment.  
     [0027]FIG. 6 is a see-through front view schematically showing the plating system according to the embodiment.  
     [0028]FIG. 7 is a side view schematically showing the plating system according to the embodiment.  
     [0029]FIG. 8 is a see-through side view schematically showing the plating system according to the embodiment.  
     [0030]FIG. 9 is a vertical sectional view schematically showing a plating unit according to the embodiment, which includes a fragmentary enlarged view.  
     [0031]FIG. 10 is a plane view schematically showing the plating unit according to the embodiment.  
     [0032]FIG. 11 is a flowchart showing the flow in the entire plating system according to the embodiment.  
     [0033]FIG. 12 is a flowchart showing the flow of plating performed in the plating unit according to the embodiment.  
     [0034]FIG. 13 is a vertical sectional view schematically showing the state in which a housing according to a conventional example is covered with a synthetic resin film. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
     [0035] Hereinafter, a plating system according to an embodiment of the present invention will be explained.  
     [0036]FIG. 1 is a perspective view schematically showing the plating system according to this embodiment, which includes a fragmentary enlarged view, and FIG. 2 is a see-through perspective view schematically showing the plating system according to this embodiment. FIG. 3 and FIG. 4 are a plane view and a see-through plane view schematically showing the plating system according to this embodiment. FIG. 5 and FIG. 6 are a front view and a see-through front view schematically showing the plating system according to this embodiment. FIG. 7 and FIG. 8 are a side view and a see-through side view schematically showing the plating system according to this embodiment.  
     [0037] As shown in FIG. 1 to FIG. 8, a plating system  1  has a housing  2  constituting an outer face of the plating system  1 . The inside of the housing  2  is divided by a partition board  22  of the housing  2 , which will be described later, into a carrier station  3  that transfers wafers W to/from carrier cassettes C housing the wafers W from/to a later-described process station  4 , and the process station  4  that processes the wafers W.  
     [0038] The carrier station  3  is composed of a mounting table  31  to mount the carrier cassettes C thereon and a sub arm  32  that takes out the wafer W from the carrier cassette C mounted on the mounting table  31  and sets the wafer W into the carrier cassette C.  
     [0039] In the carrier cassette C, a plurality of, for example, 25 wafers W are housed, being kept horizontal at equal intervals. On the mounting table  31 , for example, four carrier cassettes C are arranged in an X direction.  
     [0040] The sub arm  32  is configured to move on a rail laid in an X direction and to ascend/descend in a Z direction. The sub arm  32  is also configured to rotate on a horizontal plane.  
     [0041] The sub arm  32  has an extendable/contractible wafer holding member  33 . The wafer holding member  33  extends/contracts to take out an unprocessed wafer W from the carrier cassette C or to set a processed wafer W into the carrier cassette C. Note that the sub arm  32  transfers the wafer W also to/from the process station  4 .  
     [0042] The sub arm  32  is preferably so structured that its body itself is formed of a synthetic resin or its body is made of metal and covered airtightly with a synthetic resin film.  
     [0043] The process station  4  is vertically divided into two tiers by a dividing board  21  of the housing  2 . Specifically, the process station  4  is divided into a process section  41  positioned on an upper tier and a treatment solution supply section  42  positioned on a lower tier.  
     [0044] In the process section  41 , for example, a plating unit M 1  and a washing unit WW are disposed on a side near the carrier station  2 . Further, on a side distant from the carrier station  2 , for example, a plating unit M 2  having a plating solution with a different composition from that of a plating solution in the plating unit M 1  and an annealing unit AN are disposed.  
     [0045] In the process section  41 , a main arm  43  to carry the wafer W into each of the processing units or to carry the wafer W out of each of the processing units is disposed at the center of the aforesaid four processing units.  
     [0046] The main arm  43  is so structured to ascend/descend and also to rotate on a substantially horizontal plane. The main arm  43  is preferably so structured that its body itself is formed of synthetic resin or its body is made of metal and covered airtightly with a synthetic resin film.  
     [0047] The main arm  43  has two upper and lower wafer holding members  44  extendable/contractible on a substantially horizontal plane. The wafer holding members  44  extend/contract to carry the wafer W to/from each of the processing units.  
     [0048] The main arm  43  has a mechanism for turning the wafer W held thereby upside down. Since this mechanism is provided, the wafer W can be turned upside down while the wafer W is carried from one processing unit to another processing unit. Note that the function of turning the wafer W upside down is not a function essential to the main arm  43 .  
     [0049] In the treatment solution supply section  42 , tanks  45  in each of which, for example, a plating solution or a wash is stored, are provided. The plating unit M 1 , the plating unit M 2 , or the washing unit WW is connected to each of the tanks  45  via a pipe  46 . The plating solution or the wash is pumped up from the tank  45  with a not-shown pump to be supplied to the plating unit M 1 , the plating unit M 2 , or the washing unit WW.  
     [0050] The partition board  22  is provided between the carrier station  3  and the process station  4 . The partition board  22  has in two places thereof opening portions G 1  and G 2  which can be opened/closed.  
     [0051] The opening portion G 1  is used when the unprocessed wafer W is carried into the process station  4 . When the wafer W is to be carried in, the opening portion G 1  is opened and the sub arm  32  holding the unprocessed wafer W carries the wafer W into the process station  4 . Incidentally, the sub arm  32  places the wafer W on an intermediary mounting table  47  provided in the process station  4 .  
     [0052] The opening portion G 2  is used when the processed wafer W is carried out of the process station  4 . When the wafer W is to be carried out, the opening portion G 2  is opened and the sub arm  32  extends into the wet washing unit WW to hold the washed wafer W and carries out the wafer W from the process station  4 .  
     [0053] Hereinafter, the plating unit M 1  disposed in the process station  4  will be explained in detail.  
     [0054]FIG. 9 is a vertical sectional view schematically showing the plating unit M 1  according to this embodiment, which includes a fragmentary enlarged view, and FIG. 10 is a plane view schematically showing the plating unit M 1  according to this embodiment.  
     [0055] As shown in FIG. 9 and FIG. 10, the plating unit M 1  has a case  51 . The case  51  is preferably formed of synthetic resin or of metal covered airtightly with a synthetic resin film.  
     [0056] The inside of the case  51  is vertically divided into two tiers, namely, a first process section A positioned on a lower tier and a second process section B positioned on an upper tier.  
     [0057] A plating solution tank  52  is disposed inside the first process section A. The plating solution tank  52  is formed of a dual tank consisting of an inner tank  52 A and an outer tank  52 B disposed outside the inner tank  52 A.  
     [0058] The inner tank  52 A is formed in a substantially cylindrical shape with a closed bottom. An ejecting pipe  53  that ejects a plating solution from a bottom face side to an upper face of the inner tank  52 A protrudes into the inner tank  52 A. An anode electrode  54  in a substantially disk shape that is formed by, for example, the assembly of a plurality of copper balls is provided to surround the ejecting pipe  53 .  
     [0059] A diaphragm  55  vertically partitioning the inner tank  52 A is disposed above the anode electrode  54  between an outer periphery of an end portion of the ejecting pipe  53  and the inner tank  52 A. The diaphragm  55  is structured so as to transmit ions and not to transmit impurities generated when the anode electrode  54  dissolves and bubbles, for example, oxygen and hydrogen generated during plating processes.  
     [0060] The plating solution is supplied from the ejecting pipe  53  to an upper side of the inner tank  52 A partitioned by the diaphragm  55  (hereinafter, referred to as an ‘upper side of the inner tank’). The plating solution is supplied from a circulation pipe  56 , which will be described later, to a lower side of the inner tank  52 A partitioned by the diaphragm  55  (hereinafter, referred to as a ‘lower side of the inner tank’).  
     [0061] Circulation pipes  56  and  57  are provided at positions deviated from the center of the bottom face of the inner tank  52 A. A not-shown pump is disposed between the circulation pipes  56  and  57 . The operation of the not-shown pump causes the plating solution to circulate between the circulation pipes  56  and  57 .  
     [0062] The outer tank  52 B is formed in a substantially cylindrical shape with a closed bottom similarly to the inner tank  52 A. A pipe  58  is connected to the bottom portion of the outer tank  52 B, and a pump  59  is provided between the pipe  58  and the ejecting pipe  53 . When the pump  59  is operated, the plating solution which has been stored in the outer tank  52 B after overflowing from the inner tank  52 A is supplied again to the upper side of the inner tank  52 A.  
     [0063] The tank  45  in which the plating solution is stored is connected to the pipe  58  via the pipe  46 .  
     [0064] In the second process section B, a driver  61  to hold the wafer W is provided directly above the center of the plating tank  52 . The driver  61  is composed of a holder  62  to hold the wafer W and a motor  63  to rotate the wafer W together with the holder  62  on a substantially horizontal plane.  
     [0065] As shown in the fragmentary enlarged view in FIG. 9, convex contacts  64  through which a voltage is applied to the wafer W are arranged on an inner side of a bottom face of the holder  62  at positions equally dividing the bottom face to 248 portions.  
     [0066] Each of the contacts  64  is electrically connected to a not-shown external power supply via a lead wire. The wafer W having a seed layer formed on a surface to be plated thereof is mounted on the contacts  64 . Consequently, the voltage applied to the contacts  64  is also applied to the surface to be plated of the wafer W.  
     [0067] A seal member  65  is provided on the inner side of the bottom face of the holder  62 . When the wafer W is held, the seal member  65  is pressed via the wafer W. Since the seal member  65  is pressed, the plating solution is prevented from entering the inner side of the holder  62 .  
     [0068] A hoisting/lowering mechanism  66  to hoist/lower the driver  61  relatively to the plating solution tank  52  is attached to the motor  63 . The hoisting/lowering mechanism  66  is mainly composed of a support beam  67  attached to an outer case of the motor  63  and supporting the driver  61 , a guide rail  68  attached to an inner wall of the case  51 , and a cylinder  69  extendable/contractible in a vertical direction that hoists/lowers the support beam  67  along the guide rail  68 . When the cylinder  69  is driven, the driver  61  supported by the support beam  67  moves up/down along the guide rail  68  to hoist/lower the wafer W.  
     [0069] Specifically, with the hoisting/lowering mechanism  66 , the wafer W ascends/descends to positions different in height, that is, a transfer position (I) for transfer, a wafer washing position (II) for washing the plated surface of the wafer W with a wash, for example, a pure water, a contact washing position (III) for washing the contacts  64  with a wash, for example, a pure water, a spin dry position (IV) for spin drying for removing an unnecessary plating solution and moisture, and a plating position (V) for plating the wafer W. The transfer position (I), the wafer washing position (II), and the contact washing position (III) are higher than the level of the plating solution when the inner tank  52 A is filled with the plating solution, and the spin dry position (IV) and the plating position (V) are lower than the level of the plating solution.  
     [0070] A separator  72  having a washing nozzle  70  and an exhaust port  71  provided therein is disposed between the first process section A and the second process section B. A through hole is provided at the center of the separator  72  so as to allow the wafer W held by the driver  61  to move between the first process section A and the second process section B.  
     [0071] A gate valve  73  through which the wafer W is carried into/out of the plating unit M 1  is provided in a portion corresponding to the border between the first process section A and the second process section B of the case  51 .  
     [0072] Next, the housing  2  of the plating system  1  will be explained in detail.  
     [0073] The housing  2  is composed of a frame  23  and a plurality of panels  24  fitted into a space surrounded by the frame  23 . The frame  23  and the panels  24  are formed of metal, for example, iron.  
     [0074] The frame  23  is formed in such a manner that pipes having a square sectional shape or pipes having a circular sectional shape are bent and welded together. Incidentally, the square pipes or the circular pipes can be formed by a common method, for example, extrusion.  
     [0075] Each of the panels  24  is formed in a flat plate shape by a common method, for example, rolling. The panels  24  are used as side boards, a top board, a bottom board, a carrier cassette mounting board, the dividing board  21 , and the partition board  22  of the plating system  1 .  
     [0076] The frame  23  and the panels  24  are covered with films  25  formed of synthetic resin. Here, in this embodiment, the films  25  cover the whole outer periphery of the frame  23  and the whole surfaces of the panels  24  respectively. Heat contraction is utilized to cover the frame  23  and the panels  24  with the films  25 . The heat contraction means that the films  25  contract when the films  25  are heated.  
     [0077] In order to cover the frame  23  and the panels  24  through the utilization of the heat contraction, the films  25  are first formed, for example, in a tube shape by a common method such as extrusion. Next, the films  25  formed in the tube shape are made to cover the frame  23  and the panels  24 , and thereafter heated by a not-shown heating unit. This heating causes the films  25  to contract so that the frame  23  and the panels  24  are covered with the films  25 . Here, an adhesive is not used when the frame  23  and the panels  24  are covered with the films  25  through the heat contraction of the films  25 .  
     [0078] Concretely, as the synthetic resin forming the films  25 , it is preferable to use at least any one thermoplastic synthetic resin out of, for example, polyethylene (PE), polypropylene (PP), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), liquid crystal polymer (LCP), polysulfone (PSU), polyethersulfone (PES), polyarylate (PAR), polyamideimide (PAI), polyetherimide (PEI), polyimide (PI), polyamide (PA), polyacetal (POM), polybutylene terephthalate (PBT), GF-reinforced polyethylene terephthalate (GF-PET), polycarbonate (PC), polyphenyleneether (PPE), acrylonitrile-butadiene-styrene (ABS), polystyrene (PS), methyl methacrylate (PMMA), and polyvinyl chloride (PVC). The thermoplastic synthetic resin is preferable because it is excellent in plating solution resistance, workability, strength, and so on.  
     [0079] Further, among all of the above, it is more preferable to use at least any one synthetic resin out of polyetheretherketone (PEEK), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). These synthetic resins are more preferable because they are more excellent in plating solution resistance, workability, strength, and so on.  
     [0080] Moreover, these synthetic resins do not contain a large volume of additive, for example, plasticizer, fire retardant, and antioxidant. This avoids the situation that a polymer contained in the additive vaporizes to scatter in a clean room, which can prevent the contamination of the wafer W.  
     [0081] The thickness of the films  25  is preferably 0.1 mm or less. The thickness of the films  25  is set to 0.1 mm or less because the thickness of more than 0.1 mm makes the covering difficult and causes cost increase.  
     [0082] In this embodiment, since the heat contraction is utilized to cover the frame  23  and the panels  24  with the films  25 , the frame  23  and the panels  24  can be maintained airtight. As a result, the corrosion of the housing  2 , more particularly, the corrosion of the frame  23  and the panels  24  constituting the housing  2  can be prevented.  
     [0083] To be more specific, when the heat contraction of the films  25  occurs, the films  25  come in close contact with the surfaces of the frame  23  and the panels  24 , as shown in the fragmentary enlarged view in FIG. 1. Owing to the close contact of the films  25 , spaces are not easily formed between the films  25  and the frame  23  or between the films  25  and the panels  24 . As a result, the frame  23  and the panels  24  are not easily corroded even when the mist of the plating solution generated in the plating unit M 1  is discharged when the wafer W is carried in/out to scatter in the housing  2 .  
     [0084] Since the heat contraction of the films  25  is utilized, the frame  23  and the panels  24  can be covered easily. Moreover, the films  25  need not be welded together, and therefore, no hole formed due to insufficient welding occurs.  
     [0085] Since the heat contraction of the films  25  is utilized, it is possible to cover the frame  23  and the panels  24  regardless of bases. As a result, no pretreatment such as a blast process is required, which can realize cost reduction.  
     [0086] Since the heat contraction of the films  25  is utilized, even when, for example, two pipes different in diameter are welded together to form the frame  23 , the film  25  comes in close contact with a welded portion where the diameter changes. As a result, a space does not easily occur in the welded portion.  
     [0087] Here, since two pipes are heated and joined together at each welded portion of the frame  23 , the welded portion of the frame  23 , in which the metal composition is changed, is especially subject to corrosion. In this embodiment, however, since the close contact state of the films  25  is obtained through the heat contraction, it is possible to maintain the welded portions of the frame  23  airtight to prevent corrosion.  
     [0088] Further, since no adhesive is used when the frame  23  and the panels  24  are covered, it is possible to reduce the total thickness of the film  25  and the frame  23  or the film  25  and the panel  24  and to realize cost reduction as well.  
     [0089] Hereinafter, the process performed in the plating system  1  will be explained. FIG. 11 is a flowchart showing the flow of the entire plating system  1  according to this embodiment, and FIG. 12 is a flowchart showing the flow of plating performed in the plating unit M 1  according to this embodiment.  
     [0090] The carrier cassette C housing one lot of the wafers W, for example, 25 wafers W is mounted on the mounting table  31  of the carrier station  3  (Step  1 ).  
     [0091] When the carrier cassette C is mounted on the mounting table  31 , the sub arm  32  moves to the front of the carrier cassette C to take an unprocessed wafer W out of the carrier cassette C mounted on the mounting table  31 .  
     [0092] Thereafter, the sub arm  32  rotates, and at the same time, the wafer holding member  33  holding the wafer W extends to temporarily mount the wafer W on the intermediary mounting table  47  via the opening portion G 1 .  
     [0093] When the wafer W is mounted on the intermediary mounting table  47 , the wafer holding member  44  extends to receive the wafer W on the intermediary mounting table  47 . After the wafer holding member  44  receives the wafer W, the main arm  43  rotates, and at the same time, turns the wafer W upside down.  
     [0094] Thereafter, the wafer holding member  44  extends to carry the wafer W into the plating unit M 1 .  
     [0095] When the wafer W is carried into the plating unit M 1 , plating is started and the surface to be plated of the wafer W is plated according to the flow shown in FIG. 12 (Step  2 ), (Step  2 ( 1 ) to Step  2 ( 14 )). Here, when the wafer W is carried into the plating unit M 1  or carried out of the plating unit M 1 , the gate valve  73  is opened, so that the mist of the plating solution in the plating unit M 1  scatters in the plating system  1 . In this embodiment, however, since the housing  4  is covered airtightly with the synthetic resin films  25 , the corrosion of the frame  23  and the panels  24  can be prevented even when the mist of the plating solution scatters in the plating system  1 .  
     [0096] After the plating is finished in the plating unit M 1 , the wafer W held by the wafer holding member  44  is carried into the plating unit M 2 , if necessary, in which the plating solution different in composition is stored, and the wafer W is plated therein.  
     [0097] After a series of the plating processes is finished, the wafer holding member  44  holding the wafer W carries the wafer W into the washing unit WW, where the plated surface and the rear surface of the wafer W are washed (Step  3 ).  
     [0098] After the plated surface and the rear surface of the wafer W are washed, the wafer W is annealed in the annealing unit AN (Step  4 ).  
     [0099] After the wafer W is annealed, the main arm  43  receives the wafer W again to deliver the wafer W to the sub arm  32  via the washing unit WW. Next, the wafer holding member  33  extends to return the wafer W having subjected to a series of the processes into the carrier cassette C. Thereafter, the wafer W is carried to another treatment system performing subsequent treatment (Step  5 ).  
     [0100] It should be noted that the present invention is not limited to the described contents of the above embodiment, and any appropriate change in the structure, the material, the arrangement of the members, and so on may be made therein without departing from the spirit of the present invention. For example, the frame  23  and the panels  24 , though formed of metal in the above-described embodiment, need not be formed of metal.  
     [0101] In the above-described embodiment, the whole periphery of the frame  23  and the whole surfaces of the panels  24  are covered with the films  25 , but the films  25  may cover only parts of the frame  23  and the panels  24 , that is, portions especially subject to corrosion.  
     [0102] In the above-described embodiment, the heat contraction is utilized to cover the frame  23  and the panels  24  with the films  25 , but lamination may be utilized to cover the frame  23  and the panels  24  with the films  25 . Here, the lamination means to paste a synthetic resin film onto a base material such as metal with an adhesive. The utilization of the lamination makes it possible to cover the frame  23  and the panels  24  more airtightly.  
     [0103] The lamination includes, for example, dry lamination and hot melt lamination.  
     [0104] The dry lamination is a method in which a film is dried after being coated with an adhesive, and thereafter, bonded by thermal contact. As the adhesive in this case, usable are, for example, a vinyl-based resin, an acryl-based resin, a polyamide-based resin, an epoxy-based resin, a rubber-based resin, and a urethane-based resin.  
     [0105] The hot melt lamination is a method in which a synthetic resin film dissolved by heating is coated with an adhesive and is pasted onto a base material as it is. For example, the adhesive including EVA, polyester, styrene elastomer or polyamide as a base polymer can be used in this case.  
     [0106] In the above-described embodiment, the frame  23  and the panels  24  which are made of metal are covered with the synthetic resin films  25 , but the frame  23  and the panels  24  themselves may be formed of synthetic resin by extrusion or the like. Forming the frame  23  and the panels  24  themselves of synthetic resin can make the frame  23  and the panels  24  free of corrosion. This case is not limited to forming the whole frame  23  and the whole panels  24  of the synthetic resin, but parts of the frame  23  and the panels  24 , that is, only portions especially subject to corrosion may be formed of synthetic resin. Further, when the frame  23  and  24  are formed, covering them with the films  25  and forming them of synthetic resin may be combined.  
     INDUSTRIAL APPLICABILITY  
     [0107] A fluid treatment system according to the present invention is usable in the semiconductor manufacturing industry.